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Faculty of Engineering

Department of Computer Engineering

Purchasing and Selling Computer PartsVisual Basic

Graduation ProjectCOM-400

Student Name: Ahmad Moh'd Eid(20020934)

Supervisor: Assist.Prof Dr. Firudin Muradov

Nicosia - 2007

ACKNOWLEDGEMENT

First of all I would like to thanks ALLAHfor guiding me through my study.

More over I feel proud to pay my special regards to my project adviser "Assist.Prof Dr.

Firudin Muradov ". He never disappointed me in any affair. He delivered me too much

information and did his best of efforts to make me able to complete my project. He has

Devine place in my heart and I am less than the halfwithout his help. I am really thankful

to my teacher.

Also, I want to pay special regards to my parents who are enduring these all expenses

and supporting me in all events. I am nothing without their prayers. They also

encouraged me in crises. I shall never forget their sacrifices for my education so that I

can enjoy my successful life as they are expecting. They may get peaceful life in Heaven.

At the end I am again thankful to those all persons who helped me or even encouraged

me to complete me, myproject. My all efforts to complete thisproject might befruitful.

To the best of my knowledge, I want to honor those all people who have supported me or

helped me in my project. I also pay my special thanks to my all friends who have helped

me in myproject and gave me theirprecious time to complete myproject.

ABSTRACT

This project is a package program to store the company daily transaction concerning

purchasing and selling computer parts.

The project uses Microsoft Visual Basic 6.0, Microsoft Access XP for creating Data

Base and some SQL Queries to manage database.

The aim of this project is to help the user to manage the data storage and use it when

it is needed.

Customers pass by in computer shops to search for the best quality computer parts

and prices, some customers pay in cash and some pay by using credit cards. So, the

selling operation must be managed and controlled daily. On the other hand the company

must hire employees with full information about them in which they can help the

customers in finding the computer parts and writing full information about the product

sells with the customer information.

This program helps user to manage the whole information in general and save it in

database so they can use it later when it's needed.

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Table of Contents

ACKNOWLEDGEMENT

ABSTRACT

CONTENTS

INTRODUCTION

1. DATABASE

1 .1 Overview

1.2 History

1 .3 Database models

1 .3. 1 Flat model

1 .3 .2 Hierarchical model

1.3.3 Network model

1 .3.4 Relational model

1.3.4.1 Relational operations

1.3.5 Dimensional model

1.3.6 Object database models

1 .4 Database internals

1. 4. 1 Indexing

1 .4.2 Transactions and concurrency

1 .4.3 Replication

1 .5 Applications of database

2. SQL

2. 1 What is SQL

2.2 History

2.3 Standardization

2.4 Scope

2.5 Reasons For Lack Of Portability

2.6 SQL keywords

2.6.1 Data retrieval

2.6.2 Data manipulation

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2.6.3 Data transaction

2.6.4 Data definition

2.6.5 Data control

2.7 Criticisms of SQL

2.8 Alternatives to SQL

3. MICROSOFT ACCESS

3.1 Over View

3.2 History

3.3 Uses

3 .4 Features

3.5 Development

4. VISUAL BASIC

4.1 Over View

4.2 Derivative languages

4.3 Language features

4.4 Controversy

4.4.1 Weaknesses

4.4.1.1 Performance

4.4.1.2 Error Handling

4.4.1.3 Simplicity

4.4.2 Strengths

4.4.2.1 Debugging

4.4.2.2 Simplicity

4.4.3 Programming constructs not present in Visual Basic

4.4.4 Characteristics present in Visual Basic

4.5 Evolution of Visual Basic

4.6 Timeline of Visual Basic (VBl to VB6)

5. DESCRIPTION OF THE SOFTWARE

5 .1 Introduction

5.2 Description of the forms

CONCLUSION

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REFERENCES

APPENDIX 60

61

V

INTRODUCTION

This project describes database system concepts and a simple computer shop program

which named purchasing and selling computer parts. The application part uses Access

and SQL quires. The program is written by Microsoft Visual Basic 6.0, and Microsoft

Access XP to create database.Also it uses some SQL codes.

The project contains five chapters.

CHAPTER 1: describes information about the database in general, database models,relational database operations and brands.

CHAPTER 2: describes basics of SQL. Its history, keywords and some of thecommands of it.

CHAPTER 3: describesMicrosoft Access and its features.

CHAPTER 4: presents information about Visual Basic Language Features and the

basic concepts of VisualBasic.

CHAPTER 5: describes the program execution and basics about purchasing andselling computerparts,

vı

CHAPTER ONE

DATABASE

1.1 Overview

The term database originated within the computer industry. Although its meaning

has been broadened by popular use, even to include non-electronic databases, this

article takes a more technical perspective. A possible definition is that a database is a

collection of records stored in a computer in a systematic way, so that a computer

program can consult it to answer questions. The items retrieved in answer to queries

become information that can be used to make decisions. The computer program used

to manage and query a database is known as a database management system (DBMS).

The properties and design of database systems are included in the study of

information science.

The central concept of a database is that of a collection of records, or pieces of

knowledge. Typically, for a given database, there is a structural description of the type

of facts held in that database: this description is known as a schema. The schema

describes the objects that are represented in the database, and the relationships among

them. There are a number of different ways of organizing a schema, that is, of

modeling the database structure: these are known as database models (or data

models). The model in most common use today is the relational model, which in

layman's terms represents all information in the form of multiple related tables each

consisting of rows and columns (the true definition uses mathematical terminology).

This model represents relationships by the use of values common to more than one

table. Other models such as the hierarchical model and the network model use a more

explicit representation of relationships.

Strictly speaking, the term database refers to the collection of related records, and

the software should be referred to as the database management system or DBMS.

When the context is unambiguous, however, many database administrators and

programmers use the term database to cover both meanings.

1

Many professionals would consider a collection of data to constitute a database

only if it has certain properties: for example, if the data is managed to ensure its

integrity and quality, if it allows shared access by a community of users, if it has a

schema, or if it supports a query language. However, there is no agreed definition of

these properties.

Database management systems are usually categorized according to the data

model that they support: relational, object-relational, network, and so on. The data

model will tend to determine the query languages that are available to access the

database. A great deal of the internal engineering of a DBMS, however, ıs

independent of the data model, and is concerned with managing factors such as

performance, concurrency, integrity, and recovery from hardware failures. In these

areas there are large differences between products.

1.2 History

The earliest known use of the term 'data base' was in June 1963, when the System

Development Corporation sponsored a symposium under the title Development and

Management of a Computer-centered Data Base. Database as a single word became

common in Europe in the early 1970s and by the end of the decade it was being used

in major American newspapers. (Databank, a comparable term, had been used in the

Washington Post newspaper as early as 1966.)

The first database management systems were developed in the 1960s. A pioneer in

the field was Charles Bachman. Bachrnan's early papers show that his aim was to

make more effective use of the new direct access storage devices becoming available:

until then, data processing had been based on punched cards and magnetic tape, so

that serial processing was the dominant activity. Two key data models arose at this

time: CODASYL developed the network model based on Bachrnan's ideas, and

(apparently independently) the hierarchical model was used in a system developed by

North American Rockwell, later adopted by IBM as the cornerstone of their IMS

product.

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The relational model was proposed by E. F. Codd in 1970. He criticized existing

models for confusing the abstract description of information structure with

descriptions of physical access mechanisms. For a long while, however, the relational

model remained of academic interest only. While CODASYL systems and IMS were

conceived as practical engineering solutions taking account of the technology as it

existed at the time, the relational model took a much more theoretical perspective,

arguing (correctly) that hardware and software technology would catch up in time.

Among the first implementations were Michael Stonebraker's Ingres at Berkeley, and

the System R project at IBM. Both of these were research prototypes, announced

during 1976. The first commercial products, Oracle and DB2, did not appear until

around 1980. The first successful database product for microcomputers was dBASE

for the CP/Mand PC-DOS/MS-DOS operating systems.

During the 1980s, research activity focused on distributed database systems and

database machines, but these developments had little effect on the market. Another

important theoretical idea was the Functional Data Model, but apart from some

specialized applications in genetics, molecular biology, and fraud investigation, the

world took little notice.

In the 1990s, attention shifted to object-oriented databases. These had some

success in fields where it was necessary to handle more complex data than relational

systems could easily cope with, such as spatial databases, engineering data (including

software engineering repositories), and multimedia data. Some of these ideas were

adopted by the relational vendors, who integrated new features into their products as a

result.

In the 2000s, the fashionable area for innovation is the XML database. As with

object databases, this has spawned a new collection of startup companies, but at the

same time the key ideas are being integrated into the established relational products.

XML databases aim to remove the traditional divide between documents and data,

allowing all of an organization's information resources to be held in one place,

whether they are highly structured or not

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1.3 Database models

Various techniques are used to model data structure. Most database systems are

built around one particular data model, although it is increasingly common for

products to offer support for more than one model. For any one logical model various

physical implementations may be possible, and most products will offer the user some

level of control in tuning the physical implementation, since the choices that are made

have a significant effect on performance. An example of this is the relational model:

all serious implementations of the relational model allow the creation of indexes

which provide fast access to rows in a table if the values of certain columns are

known.

A data model is not just a way of structuring data: it also defines a set of

operations that can be performed on the data. The relational models, for example,

define operations such as select, project, and join. Although these operations may not

be explicit in a particular query language, they provide the foundation on which a

query language is built.

1.3.1 Flat model

This may not strictly qualify as a data model, as defined above. The flat (or table)

model consists of a single, two-dimensional array of data elements, where all

members of a given column are assumed to be similar values, and all members of a

row are assumed to be related to one another. For instance, columns for name and

password that might be used as a part of a system security database. Each row would

have the specific password associated with an individual user. Columns of the table

often have a type associated with them, defining them as character data, date or time

information, integers, or floating point numbers. This model is, incidentally, a basis of

the spreadsheet.

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1.3.2 Hierarchical model

In a hierarchical model, data is organized into a tree-like structure, implying a

single upward link in each record to describe the nesting, and a sort field to keep the

records in a particular order in each same-level list. Hierarchical structures were

widely used in the early mainframe database management systems, such as the

Information Management System (IMS) by IBM, and now describe the structure of

XML documents. This structure allows one 1: N relationship between two types of

data. This structure is very efficient to describe many relationships in the real world;

recipes, table of contents, ordering of paragraphs/verses, any nested and sorted

information. However, the hierarchical structure is inefficient for certain database

operations when a full path (as opposed to upward link and sort field) is not also

included for each record.

1.3.3 Network model

The network model (defined by the CODASYL specification) organizes data

using two fundamental constructs, called records and sets. Records contain fields

(which may be organized hierarchically, as in the programming language COBOL).

Sets (not to be confused with mathematical sets) define one-to-many relationships

between records: one owner, many members. A record may be an owner in any

number of sets, and a member in any number of sets.

The operations of the network model are navigational in style: a program

maintains a current position, and navigates from one record to another by following

the relationships in which the record participates. Records can also be located by

supplying key values.

Although it is not an essential feature of the model, network databases generally

implement the set relationships by means of pointers that directly address the location

of a record on disk. This gives excellent retrieval performance, at the expense of

operations such as database loading and reorganization.

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1.3.4 Relational model

The relational model was introduced in an academic paper by E. F. Codd in 1970

as a way to make database management systems more independent of any particular

application. It is a mathematical model defined in terms of predicate logic and set

theory.

The products that are generally referred to as relational databases in fact

implement a model that is only an approximation to the mathematical model defined

by Codd. The data structures in these products are tables, rather than relations: the

main differences being that tables can contain duplicate rows, and that the rows (and

columns) can be treated as being ordered. The same criticism applies to the SQL

language which is the primary interface to these products. There has been

considerable controversy, mainly due to Codd himself, as to whether it is correct to

describe SQL implementations as "relational": but the fact is that the world does so,

and the following description uses the term in its popular sense.

A relational database contains multiple tables, each similar to the one in the "flat"

database model. Relationships between tables are not defined explicitly; instead, keys

are used to match up rows of data in different tables. A key is a collection of one or

more columns in one table whose values match corresponding columns in other

tables: for example, an Employee table may contain a column named Location which

contains a value that matches the key of a Location table. Any column can be a key,

or multiple columns can be grouped together into a single key. It is not necessary to

define all the keys in advance; a column can be used as a key even if it was not

originally intended to be one.

A key that can be used to uniquely identify a row in a table is called a unique key.

Typically one of the unique keys is the preferred way to refer to a row; this is defined

as the table's primary key.

A key that has an external, real-world meaning (such as a person's name, a book's

ISBN, or a car's serial number) is sometimes called a "natural" key. If no natural key

is suitable (think of the many people named Brown), an arbitrary key can be assigned

(such as by giving employees ID numbers). In practice, most databases have both

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generated and natural keys, because generated keys can be used internally to create

links between rows that cannot break, while natural keys can be used, less reliably, for

searches and for integration with other databases. (For example, records in two

independently developed databases could be matched up by social security number,

except when the social security numbers are incorrect, missing, or have changed.)

1.3.4.1 Relational operations

Users (or programs) request data from a relational database by sending it a query

that is written in a special language, usually a dialect of SQL. Although SQL was

originally intended for end-users, it is much more common for SQL queries to be

embedded into software that provides an easier user interface. Many web sites, such

as Wikipedia, perform SQL queries when generating pages.

In response to a query, the database returns a result set, which is just a list of rows

containing the answers. The simplest query is just to return all the rows from a table,

but more often, the rows are filtered in some way to return just the answer wanted.

Often, data from multiple tables are combined into one, by doing a join.

Conceptually, this is done by taking all possible combinations of rows (the Cartesian

product), and then filtering out everything except the answer. In practice, relational

database management systems rewrite ("optimize") queries to perform faster, using a

variety of techniques.

There are a number of relational operations in addition to join. These include

project (the process of eliminating some of the columns), restrict (the process of

eliminating some of the rows), union (a way of combining two tables with similar

structures), difference (which lists the rows in one table that are not found in the

other), intersect (which lists the rows found in both tables), and product (mentioned

above, which combines each row of one table with each row of the other). Depending

on which other sources you consult, there are a number of other operators - many of

which can be defined in terms of those listed above. These include semi-join, outer

operators such as outer join and outer union, and various forms of division. Then there

are operators to rename columns, and summarizing or aggregating operators, and if

you permit relation values as attributes (RVA - relation-valued attribute), then

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operators such as group and ungroup. The SELECT statement in SQL serves to

handle all of these except for the group and ungroup operators.

The flexibility of relational databases allows programmers to write queries that

were not anticipated by the database designers. As a result, relational databases can be

used by multiple applications in ways the original designers did not foresee, which is

especially important for databases that might be used for decades. This has made the

idea and implementation of relational databases very popular with businesses.

1.3.5 Dimensional model

The dimensional model is a specialized adaptation of the relational model used to

represent data in data warehouses in a way that data can be easily summarized using

OLAP queries. In the dimensional model, a database consists of a single large table of

facts that are described using dimensions and measures. A dimension provides the

context of a fact (such as who participated, when and where it happened, and its type)

and is used in queries to group related facts together. Dimensions tend to be discrete

and are often hierarchical; for example, the location might include the building, state,

and country. A measure is a quantity describing the fact, such as revenue. It's

important that measures can be meaningfully aggregated - for example, the revenue

from different locations can be added together.

In an OLAP query, dimensions are chosen and the facts are grouped and added

together to create a summary.

The dimensional model is often implemented on top of the relational model using

a star schema, consisting of one table containing the facts and surrounding tables

containing the dimensions. Particularly complicated dimensions might be represented

using multiple tables, resulting in a snowflake schema.

A data warehouse can contain multiple star schemas that share dimension tables,

allowing them to be used together. Coming up with a standard set of dimensions is an

important part of dimensional modeling.

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1.3.6 Object database models

In recent years, the object-oriented paradigm has been applied to database

technology, creating a new programming model known as object databases. These

databases attempt to bring the database world and the application programming world

closer together, in particular by ensuring that the database uses the same type system

as the application program. This aims to avoid the overhead (sometimes referred to as

the impedance mismatch) of converting information between its representation in the

database (for example as rows in tables) and its representation in the application

program (typically as objects). At the same time object databases attempt to introduce

the key ideas of object programming, such as encapsulation and polymorphism, into

the world of databases.

A variety of these ways have been tried for storing objects in a database. Some

products have approached the problem from the application programming end, by

making the objects manipulated by the program persistent. This also typically requires

the addition of some kind of query language, since conventional programming

languages do not have the ability to find objects based on their information content.

Others have attacked the problem from the database end, by defining an object­

oriented data model for the database, and defining a database programming language

that allows full programming capabilities as well as traditional query facilities.

Object databases suffered because of a lack of standardization: although standards

were defined by ODMG, they were never implemented well enough to ensure

interoperability between products. Nevertheless, object databases have been used

successfully in many applications: usually specialized applications such as

engineering databases or molecular biology databases rather than mainstream

commercial data processing. However, object database ideas were picked up by the

relational vendors and influenced extensions made to these products and indeed to the

SQL language.

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1.4 Database internals

1.4.1 Indexing

All of these kinds of database can take advantage of indexing to increase their

speed, and this technology has advanced tremendously since its early uses in the

1960s and 1970s. The most common kind of index is a sorted list of the contents of

some particular table column, with pointers to the row associated with the value. An

index allows a set of table rows matching some criterion to be located quickly.

Various methods of indexing are commonly used; B-trees, hashes, and linked lists are

all common indexing techniques.

Relational DBMSs have the advantage that indexes can be created or dropped

without changing existing applications making use of it. The database chooses

between many different strategies based on which one it estimates will run the fastest.

Relational DBMSs utilize many different algorithms to compute the result of an

SQL statement. The RDBMS will produce a plan of how to execute the query, which

is generated by analyzing the run times of the different algorithms and selecting the

quickest. Some of the key algorithms that deal with joins are Nested Loops Join, Sort­

Merge Join and Hash Join

1.4.2 Transactions and concurrency

In addition to their data model, most practical databases ("transactional

databases") attempt to enforce a database transaction model that has desirable data

integrity properties. Ideally, the database software should enforce the ACID rules,

summarized here:

Atomicity: Either all the tasks in a transaction must be done, or none of them. The

transaction must be completed, or else it must be undone (rolled back).

Consistency: Every transaction must preserve the integrity constraints - the

declared consistency rules - of the database. It cannot place the data in a

contradictory state.

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Isolation: Two simultaneous transactions cannot interfere with one another.

Intermediate results within a transaction are not visible to other transactions.

Durability: Completed transactions cannot be aborted later or their results

discarded. They must persist through (for instance) restarts of the DBMS after crashes

In practice, many DBMS's allow most of these rules to be selectively relaxed for

better performance.

Concurrency control is a method used to ensure that transactions are executed in a

safe manner and follow the ACID rules. The DBMS must be able to ensure that only

serializable, recoverable schedules are allowed, and that no actions of committed

transactions are lost while undoing aborted transactions.

1.4.3 Replication

Replication of databases is closely related to transactions. If a database can log its

individual actions, it is possible to create a duplicate of the data in real time. The

duplicate can be used to improve performance or availability of the whole database

system. Common replication concepts include:

Master/Slave Replication: All write requests are performed on the master and then

replicated to the slaves

Quorum: The result of Read and Write requests is calculated by querying a

"majority" of replicas.

Multimaster: Two or more replicas sync each other via a transaction identifier.

1.5 Applications of database

Databases are used in many applications, spanning virtually the entire range of

computer software. Databases are the preferred method of storage for large multiuser

applications, where coordination between many users is needed. Even individual users

find them convenient, though, and many electronic mail programs and personal

organizers are based on standard database technology. Software database drivers are

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available for most database platforms so that application softwar can use a common

application programming interface (API) to retrieve the information stored in a

database. Two commonly used database APis are JDBC and ODBC. A database is

also a 'place where you can store data and then arrange that data easily and efficiently.

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CHAPTER TWO

SQL

2.1 What Is SQL

SQL (pronounced "ess-que-el") stands for Structured Query Language. SQL is

used to communicate with a database. According to ANSI (American National

Standards Institute), it is the standard language for relational database management

systems. SQL statements are used to perform tasks such as update data on a database,

or retrieve data from a database. Some common relational database management

systems that use SQL are: Oracle, Sybase, Microsoft SQL Server, Access, Ingres, etc.

Although most database systems use SQL, most of them also have their own

additional proprietary extensions that are usually only used on their system. However,

the standard SQL commands such as "Select", "Insert", "Update", "Delete", "Create",

and "Drop" can be used to accomplish almost everything that one needs to do with a

database. This tutorial will provide you with the instruction on the basics of each of

these commands as well as allow you to put them to practice using the SQL

Interpreter.

2.2 History

An influential paper, "A Relational Model of Data for Large Shared Data Banks",

by Dr. Edgar F. Codd, was published in June, 1970 in the Association for Computing

Machinery (ACM) journal, Communications of the ACM, although drafts of it were

circulated internally within IBM in 1969. Codd's model became widely accepted as

the definitive model for relational database management systems (RDBMS or

RDMS).

During the 1970s, a group at IBM's San Jose research center developed a database

system "System R" based upon, but not strictly faithful to, Codd's model. Structured

English Query Language ("SEQUEL") was designed to manipulate and retrieve data

stored in System R. The acronym SEQUEL was later condensed to SQL because the

word 'SEQUEL' was held as a trademark by the Hawker-Siddeley aircraft company of

the UK. Although SQL was influenced by Codd's work, Donald D. Chamberlin and

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Raymond F. Boyce at IBM were the authors of the SEQUEL language design.Their

concepts were published to increase interest in SQL.

The first non-commercial, relational, non-SQL database, Ingres, was developed in

1974 at U.C. Berkeley.

In 1978, methodical testing commenced at customer test sites. Demonstrating both

the usefulness and practicality of the system, this testing proved to be a success for

IBM. As a result, IBM began to develop commercial products based on their System

R prototype that implemented SQL, including the System/38 (announced in 1978 and

commercially available in August 1979), SQL/DS (introduced in 1981), and DB2 (in

1983).

At the same time Relational Software, Inc. (now Oracle Corporation) saw the

potential of the concepts described by Chamberlin and Boyce and developed their

own version of a RDBMS for the Navy, CIA and others. In the summer of 1979

Relational Software, Inc. introduced Oracle V2 (Version2) for VAX computers as the

first commercially available implementation of SQL. Oracle is often incorrectly cited

as beating IBM to market by two years, when in fact they only beat IBM's release of

the System/38 by a few weeks. Considerable public interest then developed; soon

many other vendors developed versions, and Oracle's future was ensured.

2.3 Standardization

SQL was adopted as a standard by ANSI (American National Standards Institute)

in 1986 and ISO (International Organization for Standardization) in 1987. ANSI has

declared that the official pronunciation for SQL is /cs kju £1/, although many

English-speaking database professionals still pronounce it as sequel.

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The SQL standard has gone through a number ofrevisions:

Year Name Alias Comments

1986 SQL-86 SQL-87 First published by ANSI. Ratified by ISO in

1987.

1989 SQL-89 Minor revision.

1992 SQL-92 SQL2 Major revision (ISO 9075).

1999 SQL:1999 SQL3 Added regular expression matching, recursive

quenes, triggers, non-scalar types and some

object-oriented features. (The last two are

somewhat controversial and not yet widely

supported.)

2003 SQL:2003 Introduced XML-related features, window

functions, standardized sequences and columns

with auto-generated values (including identity-

columns).

The SQL standard is not freely available. SQL: 2003 may be purchased from ISO

or ANSI. A late draft is available as a zip archive from Whitemarsh Information

Systems Corporation. The zip archive contains a number of PDF files that define the

parts of the SQL: 2003 specification.

2.4 Scope

SQL is defined by both ANSI and ISO. There are many extensions to and

variations on the version of the language. Many of these extensions are of a

proprietary nature, such as Oracle Corporation's PL/SQL, IBM's SQL PL (SQL

Procedural Language) and Sybase I Microsoft's Transact-SQL. Commercial

implementations commonly omit support for basic features of the standard, such as

the DATE or TIME data types, preferring some variant of their own. SQL code can

rarely be ported between database systems without major modifications, in contrast to

ANSI C or ANSI Fortran, which can usually be ported from platform to platform

without major structural changes.

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SQL is designed for a specific, limited purpose - querying data contained in a

relational database. As such, it is a set-based, declarative computer language rather

than an imperative language such as C or BASIC which, being general-purpose, are

designed to solve a much broader set of problems. Language extensions such as

PL/SQL bridge this gap to some extent by adding procedural elements, such as flow­

of-control constructs. Another approach is to allow programming language code to be

embedded in and interact with the database. For example, Oracle and others include

Java in the database, while PostgreSQL allows functions to be written in a wide

variety of languages, including Perl, Tel, and C.

SQL contrasts with the more powerful database-oriented fourth-generation

programming languages such as Focus or SAS in its relative functional simplicity and

simpler command set. This greatly reduces the degree of difficulty involved in

maintaining SQL source code, but it also makes programming such questions as 'Who

had the top ten scores?' more difficult, leading to the development of procedural

extensions, discussed above. However, it also makes it possible for SQL source code

to be produced (and optimized) by software, leading to the development of a number

of natural language database query languages, as well as 'drag and drop' database

programming packages with 'object oriented' interfaces. Often these allow the

resultant SQL source code to be examined, for educational purposes, further

enhancement, or to be used in a different environment.

2.5 Reasons For Lack Of Portability

There are several reasons for this lack of portability between database systems:

The complexity and size of the SQL standard means that most databases do not

implement the entire standard.

The standard does not specify database behavior in several important areas (e.g.

indexes), leaving it up to implementations of the standard to decide how to behave.

The SQL standard precisely specifies the syntax that a conforming database

system must implement. However, the standard's specification of the semantics of

language constructs is less well-defined, leading to areas of ambiguity.

16

Many database vendors have large existing customer bases; where the SQL

standard conflicts with the prior behavior of the vendor's database, the vendor may be

unwilling to break backward compatibility.

Some believe the lack of compatibility between database systems is intentional in

order to ensure vendor lock-in.

2.6 SQL keywords

SQL keywords fall into several groups.

2.6.1 Data retrieval

The most frequently used operation in transactional databases is the data retrieval

operation. When restricted to data retrieval commands, SQL acts as a declarative

language.

SELECT is used to retrieve zero or more rows from one or more tables in a

database. In most applications, SELECT is the most commonly used Data Manipulation

Language command. In specifying a SELECT query, the user specifies a description

of the desired result set, but they do not specify what physical operations must be

executed to produce that result set. Translating the query into an efficient query plan

is left to the database system, more specifically to the query optimizer.

Commonly available keywords related to SELECT include:

FROM is used to indicate from which tables the data is to be taken, as well as how

the tables JOIN to each other.

WHERE is used to identify which rows to be retrieved, or applied to GROUP BY.

WHERE is evaluated before the GROUP BY.

GROUP BY is used to combine rows with related values into elements of a

smaller set of rows.

HAVING is used to identify which of the "combined rows" (combined rows are

produced when the query has a GROUP BY keyword or when the SELECT part

17

contains aggregates), are to be retrieved. HAVING acts much like a WHERE, but it

operates on the results of the GROUP BY and hence can use aggregate functions.

ORDER BY is used to identify which columns are used to sort the resulting data.

Data retrieval is very often combined with data projection; usually it isn't the

verbatum data stored in primative data types that a user is looking for or a query is

written to serve. Often the data needs to be expressed differently from how it's stored.

SQL allows a wide variety of formulas included in the select list to project data. A

common example would be:

SELECT UnitCost * Quantity As TotalCost FROM Orders

Example 1:

SELECT * FROM books

WHERE price> 100.00 and price< 150.00

ORDER BY title

This is an example that could be used to get a list of expensive books. It retrieves

the records from the books table that have a price field which is greater than 100.00'

and less than 150.00. The result is sorted alphabetically by book title. The asterisk (*)

means to show all columns of the books table. Alternatively, specific columns could

be named.

Example 2:

SELECT books.title, count(*) AS Authors

FROM books

JOIN book authors

ON books.book number= book authors.book number- -

GROUP BY books.title

18

Example 2 shows both the use of multiple tables in a joın, and aggregation

(grouping). This example shows how many authors there are per book. Example

output may resemble:

Title Authors

SQL Examples and Guide 3

The Joy of SQL 1

How to use Wikipedia 2

Pitfalls of SQL 1

How SQL Saved my Dog 1

2.6.2 Data manipulation

First there are the standard Data Manipulation Language (DML) elements. DML

is the subset of the language used to add, update and delete data.

INSERT is used to add zero or more rows (formally tuples) to an existing table.

UPDATE is used to modify the values of a set of existing table rows.

MERGE is used to combine the data of multiple tables. It is something of a

combination of the INSERT and UPDATE elements. It is defined in the SQL:2003

standard; prior to that, some databases provided similar functionality via different

syntax, sometimes called an "upsert".

TRUNCATE deletes all data from a table (non-standard, but common SQL

command).

DELETE removes zero or more existing rows from a table.

Example:

INSERT INTO my_table (fıeldl, fıeld2, fıeld3) VALUES ('test', 'N', NULL);

19

UPDATE my_table SET fieldl = 'updated value' WHERE field2 = 'N';

DELETE FROM my_table WHERE field2 = 'N';

2.6.3 Data transaction

Transaction, if available, can be used to wrap around the DML operations.

BEGIN WORK (or START TRANSACTION, depending on SQL dialect) can be

used to mark the start of a database transaction, which either completes completely or

not at all.

COMMIT causes all data changes in a transaction to be made permanent.

ROLLBACK causes all data changes since the last COMMIT or ROLLBACK to

be discarded, so that the state of the data is "rolled back" to the way it was prior to

those changes being requested.

COMMIT and ROLLBACK interact with areas such as transaction control and

locking. Strictly, both terminate any open transaction and release any locks held on

data. In the absence of a BEGIN WORK or similar statement, the semantics of SQL

are implementation-dependent.

Example:

BEGIN WORK;

UPDATE inventory SET quantity= quantity - 3 WHERE item = 'pants';

COMMIT;

2.6.4 Data definition

The second group of keywords is the Data Definition Language (DDL). DDL

allows the user to define new tables and associated elements. Most commercial SQL

databases have proprietary extensions in their DDL, which allow control over

nonstandard features of the database system.

20

The most basic items of DDL are the CREATE and DROP commands.

CREATE causes an object (a table, for example) to be created within the database.

DROP causes an existing object within the database to be deleted, usually

irretrievably.

Some database systems also have an AL TER command, which permits the user to

modify an existing object in various ways for example, adding a column to an existing

table.

Example:

CREATE TABLE my_table (

my_fieldl INT,

my_field2 VARCHAR (50),

my_field3 DATE NOT NULL,

PRIMARY KEY (my_fieldl, my_field2))

, All DDL statements are auto commit so while dropping a table need to have close

look at its future needs.

2.6.5 Data control

The third group of SQL keywords is the Data Control Language (DCL). DCL

handles the authorization aspects of data and permits the user to control who has

access to see or manipulate data within the database.

Its two main keywords are:

GRANT - authorizes one or more users to perform an operation or a set of

operations on an object.

21

REVOKE - removes or restricts the capability of a user to perform an operation

or a set of operations.

Example:

GRANT SELECT, UPDATE ON my_table TO some_user, another_user

Other

ANSI-standard SQL supports as a single line comment identifier (some extensions

also support curly brackets or C-style /* comments * I for multi-line comments).

Example:

SELECT * FROM inventory -- Retrieve everything from inventory table

Some SQL servers allow User Defined Functions

Database systems using SQL

Comparison of relational database management systems

Comparison of truly relational database management systems

Comparison of object-relational database management systems

Comparison of SQL syntax

List of relational database management systems

List of object-relational database management systems

List of hierarchical database management systems

22

2. 7 Criticisms of SQL

Technically, SQL is a declarative computer language for use with "SQL

databases". Theorists and some practitioners note that many of the original SQL

features were inspired by, but in violation of, the relational model for database

management and its tuple calculus realization. Recent extensions to SQL achieved

relational completeness, but have worsened the violations, as documented in The

Third Manifesto.

In addition, there are also some criticisms about the practical use of SQL:

Implementations are inconsistent and, usually, incompatible between vendors. In

particular date and time syntax, string concatenation, nulls, and comparison case

sensitivity often vary from vendor-to-vendor.

The language makes it too easy to do a Cartesian join, which results in "run-away"

result sets when WHERE clauses are mistyped. Cartesian joins are so rarely used in

practice that requiring an explicit CARTESIAN keyword may be warranted.

A similar and more common problem is that of Exploding joins; this is something

between what the user desired and a full-blown Cartesian join. What happens is that

part of the relationship or criteria has not been defined, and the database engine

returns all possible combinations of records that satisfy the ill-defined query criteria.

Most often this happens in systems which use compound keys that are not respected

in the offending query; for example maybe one out of three keys will be matched,

resulting in too much information, but still less than a Cartesian join would produce.

SQL's set theory techniques and operations usually cannot also apply to column

lists. Thus, column lists cannot be computed dynamically.

The difference between value-to-column assignment in UPDATE and INSERT

can result in confusion and added work for automated SQL code generation modules.

It does not provide a standard way, or at least a commonly-supported way, to split

large commands into multiple smaller ones that reference each other by name. This

tends to result in "run-on SQL sentences" and may force one into a deep hierarchical

23

nesting when a graph-like (reference-by-name) approach may be more appropriate

and better repetition-factoring. (Views, and stored procedures can help with this, but

often require special database privileges and are not really meant for single-query

usage.) Here is an illustration for a "duplication finder" query:

Sample Table "codeTable"

locat code descript

10 AA Foo Bar

20 AA Foo Baar

30 AA Foo Bar

1 O BB Glab Zab

20 BB Glab Zab

select*

from codeTable

where locat not in (30, 50)

and code not in

(

select code

from

(select code, descript --(gets unique code-and-descript combos)

from codeTable

where locat not in (30, 50)

24

group by code, descript )

group by code

having count(*) > 1)

order by code, locat

Here we have a table of codes in which we want to find and study typos in the

descriptions that are supposed to repeat for each location. (Perhaps the repetition is

bad normalization, but sometimes one has to deal with such data from clunky old

systems.) For example, the second row in the sample data has the typo "Baar".

In this case we want to ignore codes from location 30 and 50 because we know

they are not being used right now and thus we don't care to inspect them. To do it

properly, we have to apply the filter in two different places. I see this kind of thing in

a good many queries. There may be ways around such, but they are not obvious and

not general-purpose solutions to such.

2.8 Alternatives to SQL

A distinction should be made between alternatives to relational query languages

and alternatives to SQL. The lists below are proposed alternatives to SQL, but are still

(nominally) relational. See navigational database for alternatives to relational.

IBM Business System 12 (IBM BS12)

Tutorial D

TQL - Luca Cardelli (May not be relational)

Top's Query Language - A draft language influenced by IBM BS 12. Tentatively

renamed to SMEQL to avoid confusion with similar projects called TQL.

Hibernate Query Language [2] (HQL) - A Java-based tool that uses modified SQL

Quel introduced in 1974 by the U.C. Berkeley Ingres project.

25

Object Query Language - Object Data Management Group.

Datalog

26

CHAPTER THREE

MICROSOFT ACCESS

3.1 Overview

Figure 3.1: MICROSOFT ACCESS

relational Microsoft Access (current full name Microsoft Office Access) is a

Microsoft Office , packaged with Microsoft from database management system

with a Microsoft Jet Database Engine which combines the relational Professional

.graphical user interface

;Microsoft SQL Server stored in Access/Jet, dataMicrosoft Access can use

data and software developers-compliant data container. Skilled ODBC, or any Oracle

programmers. Relatively unskilled application software use it to develop architects

and non-programmer "power users" can use it to build simple applications. It supports

(00) techniques but falls short of being a fully 00 development object-orientedsome

tool.

Microsoft Access was also the name of a communications program from

and other programs. This Microsoft ProCommMicrosoft, meant to compete with

Access proved a failure and was dropped. Years later Microsoft reused the name for

its database software.

27

3.2 History

Microsoft specified the minimum operating system for Version 1.1 as Microsoft

Windows v3.0 with 4 MB of RAM. 6 MB RAM was recommended along with a

minimum of 8 MB of available hard disk space (14 MB hard disk space

recommended).

The product was shipped on seven 1.44 MB diskettes. The manual shows a 1993

copyright date.

The software worked well with very large records sets but testing showed some

circumstances caused data corruption. For example, file sizes over 700 MB were

problematic. (Note that most hard disks were smaller than 700 MB at the time this

was in wide use). The Getting Started manual warns about a number of circumstances

where obsolete device drivers or incorrect configurations can cause data loss.

MS-Access's initial codename was Cirrus. This was developed before Visual

Basic and the forms engine was called Ruby. Bill Gates saw the prototypes and

decided that the Basic language component should be co-developed as a separate

expandable application. This project was called Thunder. The two projects were

developed separately as the underlying forms engines were incompatible with each

other; however, these were merged together again after VBA.

3.3 Uses

Access is used by small businesses, within departments of large corporations, and

hobby programmers to create ad hoc customized desktop systems for handling the

creation and manipulation of data. Access can also be used as the database for basic

web based applications hosted on Microsoft's Internet Information Services and

utilizing Microsoft Active Server Pages ASP. More complex web applications may

require tools like PHP/MySQL or ASP/Microsoft SQL Server.

Some professional application developers use Access for rapid application

development, especially for the creation of prototypes and standalone applications

that serve as tools for on-the-road salesmen. Access does not scale well if data access

28

is via a network, so applications that are used by more than a handful of people tend

to rely on a Client-Server based solution such as Oracle, DB2, Microsoft SQL Server,

Windows Share Point Services, PostgreSQL, MySQL, Alpha Five, MaxDB, or

FileMaker. However, an Access "front end" (the forms, reports, queries and VB code)

can be used against a host of database back ends, including JET (file-based database

engine, used in Access by default), Microsoft SQL Server, Oracle, and any other

ODBC-compliant product.

Many developers who use Microsoft Access use the Leszynski namıng

convention, though this is not universal; it is a programming convention, not a

DBMS-enforced rule.

3.4 Features

One of the benefits of Access from a programmer's perspective is its relative

compatibility with SQL-queries may be viewed and edited as SQL statements, and

SQL statements can be used directly in Macros and VBA Modules to manipulate

Access tables.

Users may mix and use both VBA and "Macros" for programming forms and logic

and offers object-oriented possibilities.

MSDE (Microsoft SQL Server Desktop Engine) 2000, a mini-version of MS SQL

Server 2000, is included with the developer edition of Office XP and may be used

with Access as an alternative to the Jet Database Engine.

Unlike a complete RDBMS, the Jet Engine lacks database triggers and stored

procedures. Starting in MS Access 2000 (Jet 4.0), there is a syntax that allows

creating queries with parameters, in a way that looks like creating stored procedures,

but these procedures are limited to one statement per procedure. Microsoft Access

does allow forms to contain code that is triggered as changes are made to the

underlying table (as long as the modifications are done only with that form), and it is

common to use pass-through queries and other techniques in Access to run stored

procedures in RDBMSs that support these.

29

In ADP files (supported in MS Access 2000 and later), the database-related

features are entirely different, because this type of file connects to a MSDE or

Microsoft SQL Server, instead of using the Jet Engine. Thus, it supports the creation

of nearly all objects in the underlying server (tables with constraints and triggers,

views, stored procedures and UDF-s). However, only forms, reports, macros and

modules are stored in the ADP file (the other objects are stored in the back-end

database).

3.5 Development

Access allows relatively quick development because all database tables, queries,

forms, and reports are stored in the database. For query development, Access utilizes

the Query Design Grid, a graphical user interface that allows users to create queries

without knowledge of the SQL programming language. In the Query Design Grid,

users can "show" the source tables of the query and select the fields they want

returned by clicking and dragging them into the grid. Joins can be created by clicking

and dragging fields in tables to fields in other tables. Access allows users to view and

manipulate the SQL code if desired.

The programming language available in Access is, as in other products of the

Microsoft Office suite, Microsoft Visual Basic for Applications. Two database access

libraries of COM components are provided: the legacy Data Access Objects (DAO),

only available with Access, and the new ActiveX Data Objects (ADO).

Microsoft Access can be applied to small projects but scales poorly to larger

projects involving multiple concurrent users because it is a desktop application, not a

true client-server database. When a Microsoft Access database is shared by multiple

concurrent users, processing speed suffers. The effect is dramatic when there are more

than a few users or if the processing demands of any of the users are high. Access

includes an Upsizing Wizard that allows users to upsize their database to Microsoft

SQL Server if they want to move to a true client-server database.

Since all database queries, forms, and reports are stored in the database, and in

keeping with the ideals of the relational model, there is no possibility of making a

physically structured hierarchy with them.

30

One design technique is to divide an Access application between data and

programs. One database should contain only tables and relationships, while another

would have all programs, forms, reports and queries, and links to the first database

tables. Unfortunately, Access allows no relative paths when linking, so the

development environment should have the same path as the production environment

(though it is possible to write a "dynamic-linker" routine in VBA that can search out a

certain back-end file by searching through the directory tree, if it can't find it in the

current path). This technique also allows the developer to divide the application

among different files, so some structure is possible.

31

CHAPTER FOUR

VISUAL BASIC

4.1 Over View

Visual Basic (VB) is an event driven programming language and associated

development environment from Microsoft. VB has been replaced by Visual Basic

.NET. The older version of VB was derived heavily from BASIC and enables the

rapid application development (RAD) of graphical user interface (GUI) applications,

access to databases using DAO, RDO, or ADO, and creation of ActiveX controls and

objects.

A programmer can put together an application using the components provided

with Visual Basic itself. Programs written in Visual Basic can also use the Windows

API, but doing so requires external function declarations.

In business programming, Visual Basic has one of the largest user bases.

According to some sources, as of 2003, 52% of software developers used Visual

Basic, making it the most popular programming language at that time. Another point

of view was provided by the research done by Evans Data that found that 43% of

Visual Basic developers planned to move to other languages. Visual Basic currently

competes with PHP and C++ as the third most popular programming language behind

Java and C.

4.2 Derivative languages

Microsoft has developed derivatives of Visual Basic for use in scripting. It is

derived heavily from BASIC and host applications, and has replaced the original

Visual Basic language with a .NET platform version:

• Visual Basic for Applications (VBA) is included in many Microsoft

applications (Microsoft Office), and also in several third-party products like

WordPerfect Office 2002 and ESRi ArcGIS. There are small inconsistencies in the

32

way VBA is implemented in different applications, but it is largely the same language

as VB6.

• Here is an example of the language:

To find the area of a circle

Private Sub Commandl_Click ()

pi= 3.14159265358979323846264

r = Val(Radius.Text)

a= pi* r *r

area.Text= Str$(a)

End Sub

Another Example to write the words "Hello world" on the form:

Private Sub Forml_Load()

Print "Hello World"

End Sub

• VBScript is the default language for Active Server Pages and can be used in

Windows scripting and client-side web page scripting. Although it resembles VB

in syntax, it is a separate language and it is executed by the Windows Script Host

as opposed to the VB runtime. These differences can affect the performance of an

ASP web site (namely inefficient string concatenation and absence of short-cut

evaluation). ASP and VB Script must not be confused with ASP .NET which uses

Visual Basic.Net or any other language that targets the .NET Common Language

Runtime.

• Visual Basic .NET is Microsoft's designated successor to Visual Basic 6.0, and is

part of Microsoft's .NET platform. The VB.NET programming language is a true

object-oriented language that compiles and runs on the .NET Framework.

33

VB.NET is a totally new tool from the ground up, not backwards compatible with

VB6. For this reason, it was suggested by Bill Vaughn, and wholeheartedly

embraced by the user community, that it ought to have been given an alternative

name. Visual Fred (or VFred for short) was the consensus choice. VB.NET ships

with a rudimentary utility to convert legacy VB6 code, although the inefficient

nature of the resulting code (due to major differences between the two languages)

often leads programmers to prefer manual conversion instead. Indeed, automated

conversion is seen as a fantasy.

Many users have found that automated conversion of anything more than trivial

VB6 programs is essentially impossible, with many TODO's marking incompatible

sections. A rewrite does take care of this, but a complete rewrite of a complex

program is often not practical for several reasons. First, a small company considering

a rewrite must usually choose between spending its budget on new features and

maintenance, or on conversion of a static program, which in itself adds no value.

Second, a rewrite in a new language means an extensive testing cycle, again an

expense with no corresponding market value. As a result, the migration path has not

as often been from VB6 to VB.NET, but rather to other languages and platforms such

as Java, C# and Delphi.

4.3 Language features

Figure 4.1 A typical session in Microsoft Visual Basic 6

34

Visual Basic was designed to be easy to learn and use. The language not only

allows programmers to easily create simple GUI applications, but also has the

flexibility to develop fairly complex applications as well. Programming in VB is a

combination of visually arranging components or controls on a form, specifying

attributes and actions of those components, and writing additional lines of code for

more functionality. Since default attributes and actions are defined for the

components, a simple program can be created without the programmer having to write

many lines of code. Performance problems were experienced by earlier versions, but

with faster computers and native code compilation this has become less of an issue.

Although programs can be compiled into native code executables from version 5

onwards, they still require the presence of runtime libraries of approximately 2 MB in

size. This runtime is included by default in Windows 2000 and later, but for earlier

versions of Windows it must be distributed together with the executable.

Forms are created using drag and drop techniques. A tool is used to place controls

(e.g., text boxes, buttons, etc.) on the form (window). Controls have attributes and

event handlers associated with them. Default values are provided when the control is

created, but may be changed by the programmer. Many attribute values can be

modified during run time based on user actions or changes in the environment,

providing a dynamic application. For example, code can be inserted into the form

resize event handler to reposition a control so that it remains centered on the form,

expands to fill up the form, etc. By inserting code into the event handler for a

keypress in a text box, the program can automatically translate the case of the text

being entered, or even prevent certain characters from being inserted.

Visual Basic can create executables (EXE), ActiveX controls, DLL files, but is

primarily used to develop Windows applications and to interface web database

systems. Dialog boxes with less functionality (e.g., no maximize/minimize control)

can be used to provide pop-up capabilities. Controls provide the basic functionality of

the application, while programmers can insert additional logic within the appropriate

event handlers. For example, a drop-down combination box will automatically display

its list and allow the user to select any element. An event handler is called when an

item is selected, which can then execute additional code created by the programmer to

35

perform some action based on which element was selected, such as populating a

related list.

Alternatively, a Visual Basic component can have no user interface, and instead

provide ActiveX objects to other programs via Component Object Model (COM).

This allows for server-side processing or an add-in module.

The language is garbage collected using reference counting, has a large library of

utility objects, and has basic object oriented support. Since the more common

components are included in the default project template, the programmer seldom

needs to specify additional libraries. Unlike many other programming languages,

Visual Basic is generally not case sensitive, although it will transform keywords into a

standard case configuration and force the case of variable names to conform to the

case of the entry within the symbol table entry. String comparisons are case sensitive

by default, but can be made case insensitive if so desired.

4.4 Controversy

Visual Basic is seen as a controversial language; many programmers have strong

feelings regarding the quality of Visual Basic and its ability to compete with newer

languages. It was designed to be a simple language. In the interest of convenience and

rapid development, some features like explicit variable declaration are turned off by

default, something that can be easily changed. This leads to some programmers

praising Visual Basic for how simple it is to use, but can also lead to frustration when

programmers encounter problems that the features would have detected. For instance,

in Visual Basic a common mistake is to incorrectly type the name of a variable,

creating a new variable with a slightly different name.

4.4.1 Weaknesses

4.4.1.1 Performance

Early versions of Visual Basic were not competitive at performing

computationally intensive tasks because they were interpreted, and not compiled to

machine code. Although this roadblock was removed with VB5 (which compiles to

36

the same intermediate language and uses the same back end as Visual C++, some

features of the language design still introduce overhead which can be avoided in

languages like Delphi or C++. These are more likely to be encountered in code

involving objects, methods, and properties than in strictly numerical code.

4.4.1.2 Error Handling

Visual Basic does not have exception handling with the same capabilities of C++

or Java, but the On Error facility does provide nonlocal error handling with features

similar to Windows Structured Exception Handling, including the ability to resume

after an error (a feature that is not provided by either of the other two languages,

although of dubious utility in production code).

4.4.1.3 Simplicity

Many critics of Visual Basic explain that the simple nature of Visual Basic is

harmful in the long run. Many people have learned VB on their own without learning

good programming practices. Even when VB is learned in a formal classroom, the

student may not be introduced to many fundamental programming techniques and

constructs, since much of the functionality is contained within the individual

components and not visible to the programmer. Since it is possible to learn how to use

VB without learning standard programming practices, this often leads to unintelligible

code and workarounds. Second, having many of the checks and warnings that a

compiler implements turned off by default may lead to difficulties in finding bugs.

Experienced programmers working in VB tend to tum such checks on.

Many of the criticisms fired at Visual Basic are in fact criticisms of its ancestor,

BASIC. A famous formulation by Edsger Dijkstra states, "It is practically impossible

to teach good programming to students that have had a prior exposure to BASIC: as

potential programmers they are mentally mutilated beyond hope of regeneration

(Dijkstra was no less scathing about FORTRAN, PL/I, COBOL and APL).

37

4.4.2 Strengths

4.4.2.1 Debugging

Visual Basic has a comprehensive set of debugging tools comparable to those

available in the Visual C++ products of the same time period. Features include

breakpoints, the ability to watch variables and modify watched variables while

paused, the ability to modify the point of execution, and the ability to make

modifications to code while paused, often not requiring a program restart. Arbitrary

code could be executed in the "immediate window", an online interpreter, a very

powerful feature. In some cases, these features were more capable than their

counterparts in Visual C++-for instance, edit and continue in VC was inspired by

the VB feature, and there has never been a VC equivalent of the immediate window.

Furthermore, since VB5 it has been possible to generate debug symbols for a

native executable and step into VB code in external debuggers, like the Microsoft

debugger or the VC debugger, although the implementation of VB objects makes it

difficult to debug code that uses them heavily.

4.4.2.2 Simplicity

While some detractors argue that the simplicity of Visual Basic is a weakness,

many proponents of Visual Basic explain that the simple nature of Visual Basic is its

main strength, allowing very rapid application development to experienced Visual

Basic coders and a very slight learning curve for programmers corning from other

languages. Additionally, Visual Basic applications can easily be integrated with

databases, a common requirement. For example, by using controls that are bound to a

database, it is possible to write a VB application that maintains information within the

database without writing any lines ofVB code.

Visual Basic is also a conglomerate of language features and syntax, with less

consistency, but more tolerance, than many modem programming languages. Many

language features like GoSub, On Error, and declaring the type of a variable by the

last character in the name (i.e. str$) are legacies from Visual Basie's BASIC roots, and

are included for backward-compatibility. The syntax of VB is different from most

38

other languages, which can lead to confusion for new VB programmers. For example,

the statement "Dim a, b, c As Integer" declares "c" as integer, but "a" and "b" are

declared as Variant. Another source of confusion for new programmers is the

different use of parentheses for arguments of functions and subroutines. Other

characteristics include the entry of keyword, variable and subroutine names that are

not case sensitive, and an underscore "_" must be used for a statement to span

multiple lines.

Some Visual Basic programmers perceive these as strengths needed to avoid case­

sensitive compiler errors, and accidentally omitting line-termination characters some

languages require (usually semicolons). For example, the ability to enter variable and

subroutine names in any case, coupled with the IDE's automatic correction to the case

used in the declaration, can be used to the programmer's advantage: by declaring all

names in mixed case, but entering them in lower case elsewhere, allows the

programmer to type faster and to detect typos when a token remains in lower case.

The language continues to attract much praise and criticism, and it continues to

cater to a large base of users and developers. The language is well suited for certain

kinds of GUI applications (e.g., front end to a database), but less suited for others

(e.g., compute-bound programs). Its simplicity and ease of use explain its popularity

as a tool for solving business problems - most business stakeholders do not care

about technical elegance and effectiveness, and concentrate instead on the cost

effectiveness of Visual Basic.

4.4.3 Programming constructs not present in Visual Basic.

Many of these features are implemented in Microsoft's replacement for Visual

Basic 6 and prior, VB.NET.

• Inheritance. Visual Basic versions 5 and 6 are not quite object oriented languages

as they do not include implementation inheritance. VB5 and 6 do, however,

include specification of interfaces. That is, a single class can have as many distinct

interfaces as the programmer desires. Visual Basic provides a specific syntax for

access to attributes called Property methods, and this is often implemented using

39

getters and setters in C++ or Java. Python has an equivalent notation to VB6's

property Let and Get.

• Threading support (can be done by using external Windows functions).

• C++ or Java exception handling. Error handling is controlled by an "On Error"

statement, which provides similar functionality to Windows Structured Exception

Handling.

• Typecasting. VB instead has conversion functions.

• Equivalents to C-style pointers are very limited.

• Visual Basic is limited to unsigned 8-bit integers and signed integers of 16 and 32

bits. Many other languages provide wider range of signed and unsigned integers.

• 32-bit Visual Basic is internally limited to UTF-16 strings, although it provides

conversion functions to other formats (16-bit Visual Basic is internally limited to

ASCII strings).

• Visual Basic doesn't allow constant variables to contain an array. Therefore extra

processing is required to emulate this.

While Visual Basic does not naturally support these features, programmers can

construct work-arounds to give their programs similar functionality if they desire.

4.4.4 Characteristics present in Visual Basic

Visual Basic has the following uncommon traits:

• Boolean constant True has numeric value -1. In most other languages, True is

mapped to numeric value 1. This is because the Boolean data type is stored as a

16-bit signed integer. In this construct -1 evaluates to 16 binary 1 s (the Boolean

value True), and O as 16 Os (the Boolean value False). This is apparent when

performing a Not operation on a 16 bit signed integer value O which will return

the integer value -1, in other words True= Not False. This inherent functionality

becomes especially useful when performing logical operations on the individual

bits of an integer such as And, Or, Xor and Not.

• Logical and bitwise operators are unified. This is unlike all the C-derived

languages (such as Java or Perl), which have separate logical and bitwise

operators.

40

e Vaı .iable arrav hag. a Arrays ar-ra declared by specifying tho uncer ., •.• A lowerY .1 J.\.ı ~ V V. J.Jı....LJ.U. o \.ı \.ı.1.U.1.VU. l.J. ..t.'\.ı\.lJ.ıJu.ı.5. .1.1.\.ı :.l!l::'V.I. Ul.1.U. .LV'VV .l

bounds in a way similar to Pascal and Fortran. It is also possible to use the Option

Base statement to set the default lower bound. Use of the Option Base statement

can lead to confusion when reading Visual Basic code and is best avoided by

al\V'1:YS explicitly specifying the lower bound of the array. This lower bound is not

limited to O or 1, because it can also be set by declaration. In this way, both the

lower and U_Q.I?er bounds are programmable. In more subscript-limited languages,

the lower bound ofthe array is not variable. This uncommon trait does not exist in

Visual Basic .NET and VBScript.

• Relatively strong integration with the Windows operating system and the

Component Object Model.

• Banker's rounding as the default behavior when converting real numbers to

integers.

• Integers are automatically promoted to reals in expressions involving the normal

division operator (/) so that division of an odd integer by arı even integer produces

the intuitively correct result. There is a specific integer divide operator(\) which

does truncate.

• By default, if a variable has not been declared or if no type declaration character is

specified, the variable is of type variant. However this can be changed vıith

Deftype statements such as Defint, DefBool, Defvat, DefObj, Defstr. There are

12 Deftype statements in total offered by Visual Basic 6.0.

4!15 Evolution of Visu.al Basic

\'B 1.O was introduced in 1991. The approach for connecting the programming

language to the graphical user interface is derived from a prototype developed by

Alan roo:geı· C"110d T.-1· nod Microsoft contracted with Cooner and his associates ·t.-­- _ 1 '-' ~ u.l.l\.ı .l J. }'V • .iV.J..l .1V.:)V..Ll, V .lJ.UU..\.ıL VV.lU '-' Vl'\.ı.1 lU .11...l \,.,.1 L \.V

develop Tripod into a programmable shell for Windows 3.0, under the code name

Ruby (no relation to the Ruby progranı.TP.ingIa.rıguage).

Tripod did not include a programming language at all, and Ruby contained only a

rudimentary command processor sufficient for its role as a Windows shell. Microsoft

decided to use the simple Progra.ıTı ~1arıager shell for Windows 3.0 instead of Ruby,

and combine Ruby with the Basic language to create Visual Basic.

Ruby provided the "visual" part of Visual Basic-the form designer and editing

tools-along with the ability to load dynanıic !in.k libraries containing additional

controls (then called "gizmos''). Ruby's extensible gizmos later became the VBX

interface.

4.6 Timelineof Visual Basic(VB1 to VB6)

• Project 'Thunder' was initiated.

• Visual Basic 1.0 (May 1991) was released for Windows at the Comdex/Windows

World trade show in Atlanta, Georgia.

Figure 4.2Visucl1 Basic for MS~DOS

e Visual Basic 1. O for DOS was released in September 1992. T11e language itself

was not quite compatible with Visual Basic for Windows, as it was actually the

next version of Microsoft's DOS-based BASIC compilers, QuickBASIC and

BASIC Professional Development System. The interface was textual, using

extended i\.SCII characters to simulate the appearance of a GlJI.

• Visual Basic 2.0 was released in November 1992. The programming environment

was easier to use, and its speed was improved. Notably, forms became instantiable

objects, thus laying the foundational concepts öf class modules as were later

offered in VB4.

• Visual Basic 3.O was released in the summer of 1993 and came in Standard and

Professional versions. \'B3 included version 1.1 of the l\1icrosoft Jet Database

Engine that could mad and write Jet (or Access) I.x databases.

42

• Visual Basic 4.0 (August 1995) was the first version that could create 32-bit as

well as 16-bit Windows programs. It also introduced the ability to write non-GUI

classes in Visual Basic.

• With version 5.0 (February 1997), Microsoft released Visual Basic exclusively for

32-bit versions of Windows. Programmers who preferred to write 16-bit programs

were able to import programs written in Visual Basic 4.0 to Visual Basic 5.0, and

Visual Basic 5.0 programs can easily be converted with Visual Basic 4.0. Visual

Basic 5.0 also introduced the ability to create custom user controls, as well as the

ability to compile to native Windows executable code, speeding up calculation­

intensive code execution.

• Visual Basic 6.0 (Mid 1998) improved in a number of areas, including the ability

to create web-based applications. VB6 is currently scheduled to enter Microsoft's

"non-supported phase" starting March 2008.

• Mainstream Support for Microsoft Visual Basic 6.0 ended on March 31, 2005.

Extended support will end in March 2008. In response, the Visual Basic user

community expressed its grave concern and lobbied users to sign a petition to

keep the product alive. Microsoft has so far refused to change their position on the

matter. Ironically, around this time, it was exposed that Microsoft's new anti­

spyware offering, Microsoft AntiSpyware, was coded in Visual Basic 6.0.

Windows Defender Beta 2 was rewritten as C++/CLI code, as mentioned in Paul

Thurrott's review of this product.

43

CHAPTER FIVE

DESCRIPTION OF THE SOFTWARE

5.1 Introduction

Microsoft Visual Basic 6.0 has many special tools to create a project. After opening

the Visual Basic, a form is displayed to ask the user what kind of project is to be selected.

Click Standard Exe then (open) button.

Figure 5.1 Starting a New Project

44

Figure 5.2 A new form will appear and by double clicking this form you can start

writing VB codes.

45

'·~·tl- F«-fo7(f0tm7,frro);f}··f&ıJ Moduesrk·41JDesıgnt!fs

'< g o.taErMJ<m,mtı ('·'11 c,.ı;.ııeportı: g o.taRoport2' .. g o.taReport3~.go.taRoport4' ··'11 o.taRoportS

Pr aver.e dat.ab~e ~ A.DODB.Co.nnectionPrivac.e rs .13 ADOD&.Recoı;:Q$et

.....r.£.~.Y.~.~~....~sı.~.~.;.;: ....~ .... ~.~.~.1..~9Pcıvate Sub Coımıand1_Click.O

COUll

COl"IB"n6.n.dZ. Ina.bled "' Tı; ueCom:ııand3. E:nabled • Fal3eCo.ımıand.4.tnabled • falı,eText2 . sec reeue!:nd SUbPrivate Sub Conwnand2 Click: (lD1:ns en ı , a.!Jk, aexı. -as k • .P!~gBox("Do You ¥a.ne TP Save That ?"", vblntorrnatl.orı ·U. ask • vbYes ~nIt: Text.2,Texı:. -<> •• ., And fta.,kEdBoxı.Text -<> ,.,. And Text.S.Ttec ı • "f nae r t; ınto enıp (empneme , etepeocıe , elrıpphone., eınp~c,!!Ql • eqı 'eq ı . ac ı

Figure 5.3 After finishing with writing the codes click the start button from the

Visual Basic menu or easily press F5 button from Keyboard. The Program will start

running unless there are errors on the code.

46

>.s A.DODE .ccnnecc ton

Form1 (F«mı,frm_)tı FonıHO (f()rfl)JO.fitı

f-·vtl. Formll {Fomı11Jmı· ;'.•. ····~. Form1'2 (F. onr,12.frıı·:·.• •. :; .... ti,. Form2 (F«.m2Jrm) ft f>··tl Form3 {F0t·m'.3Jrm} f J• .. l:l Form< (formH,m) tffi!

· t=l fontıS (FcfmS,ftm) fj[! .•tı, Form6(Form6.frrn) fut'· ~ Fom'l7 (Foim7 .frmY ·...

&i'' Private r·s, ce ı J.g illODlLReccxctee ePrivate ·sqlStr .A.:, StringPciva~gl,,m,~Sl.!J,t_:ı:9,lZ~?.9lJM,Ztrin~~,,,mPr rveue Sub CoMııe:ndl_Cl tc:k: OMtab~:,e. C JoeeUnload Het.J.rı.J.oad roı::-ı:n.storml.Shov!ornıl. Enabled • Truet:nd Subpc tvee.e Stıl::ı CO.t11)ı&.nd2_Cliclıı:()datN>o.:,e. C j oseT.J.rı.J.oad Pieform.5. Cormıand?. Vi:,ible: • reıeeforın.5. Show

Figure 5.4 After testing the project if every thing works fine click the Visual Basic

Menu File and then Save Project button, all the changes will be saved.

47

Ctr\+5

Ctrf+P

Figure 5.5 Saving a project and Making Executable file of the project is very easy.

By clicking File Menu of Visual Basic then select make EXE selection here.

5.2 Description of the forms

Figure 5.6 Security

48

In this form users should enter their users name and password to start the program.

If the user typed a wrong usemame or password a message will be displayed saying

invalid usemame or password, otherwise the user will enter the program successfully.

Figure 5.7 Main Menu

This is the main menu form, in this form there are 8 commands and each command

gives different informationwhen you press any one of them.

For the firm records command it will lead you to the firm form, the customer records

command will lead you to customer form, employee records will lead you to employee

form, account revenue command will lead you to account form, report command will

lead you to reports form, user management command will lead you to user management

form, about command will lead you to about form, and the exit command will lead you

out of the program.

49

FIRMS RECORDS

Firm Tax fl.6:

Firm Cif;ı/ ı·-· .,

lfırm_Add~ei~:L __ ...[lflrmRegD~t~{:~

Search For firm:--------

Figure 5.8 Firm record

This is a firm record form, here we can add different firm records with their stocks. In

this form we can search, save, update and delete firms according to the firm code. Once a

new firm is added also their stocks are added in the database.

50

Figure 5.9 Stock record

This is a stock record, here stocks are separated according to their firms. We can

search, add, save, delete and edit stocks of computer products. This form shows us the

product of the stocks that are available.

51

Eırıpıôieef:ıij:l~eAdd7~'Empployee Reg.Date:

Figure 5.10 Employeerecord

This is an Employee record which shows us all the information needed about an

employee, we might want to hire a new employee or we might want search, delete or

update information about him or her. So it's so useful and saves time. This employee

application form displays for us all the informationwe need to know about the person.

52

Figure 5.11 Customer record

This is a customer form which shows us the details of a customer who is willing to

buy a stock from the shop. Here we can add, search, delete and update the customer

information.

53

Figure 5.12 Invoice

The invoice form for selling stocks to the customers contains two types of payments,

Cash or credit. This invoice will give us information about stock unit, name, amount,

price and minimum level .At the end the sub total Include tax is calculated.

54

Figure 5.13 Account revenue

This credit form shows us all the list of credit payments.

This form shows us what the company owes, once the customer pays his or her

debits. The company will register the credit form in his or her invoice form.

55

serect, The\:Report; ,- ·· ··· · _>is-·)'

Figure 5.14 Repot

This is a report form,which summaries the whole adding and selling events.

Here we have five reports, first the firm general report that show us a general

information about the firms and their stock, second we'll have the stock report which

shows us the stock code, name, quantity and the minimum level, third we'll have the

customer report which shows us the customer code, name, phone, address and the

registration date. Fourth we'll have the employee report which shows us the employee

code, name, phone and salary, at the end we'll have the invoice report which shows us the

invoice, customer and stock code, also the quantity price and the total invoice.

56

Password:

,Search For Usernemet.Fmd j !,,.,,.,,,._...__-__ _.

New.J

Figure 5.15 User management

This is an administration management form, in this form you can change the

administer names and password, also you can add a new administer or search, update and

delete them from the administration form by the database.

57

Record Not Exist

Figure 5.16 stock min levels

This form informs me how many stocks are available in the stock room.

When I run out of item this message will appear on my screen to inform me that I am

running out of the minimum stock level.

58

I /\. //'t({ l' I ,- :J •c.;..-. • - ••• I ~ ~.. .

~

o l ,!),, ,;'?'-//

Database management has evolved from a specialized computer applic ~~~~fy ....._ -

central component of a modem computing environment. As such, knowledge about

CONCLUSION

database systems has become an essential part of an education in computer science. Our

purpose in this project is to present the fundamental concepts of database management.

These concepts include aspects of database design, and database-system implementation.

The software described in the project is prepared by Visual Basic 6.0 and Microsoft

Access XP. Both of them are powerful tools to create and operate sophisticated data

organizations.

Visual Basic 6.0 has many tools to help programmer. However, there are new editions

of Visual Basic, the version 6.0 is preferred, to show that this version is also sufficient to

make good software.

This project contains many examples of using database (SQL) quires like deleting,

updating and inserting information's in the data.

59

REFERENCE

[1] http://www.Wikipedia.com

[2] http://www.sqlcourse.com/table.html

[3] http://www.howstuffworks.com

[4] http//www.Computerhope.com

[5] http://www.google.com

[6] Sams Teach Yourself Microsoft Access 2000 in 21 Days

[7] http//www.yahoo.com

[8] Visual Basic 6 Black Book

[9] Sam's Teach Yourself MySQL in 21 Days

[10) www.VisualBasic.com

60

APPENDIX SOURCE CODE LISTINGS

The user name form

Dim sqlstr As StringDim database As ADODB.ConnectionDim rs As Recordset

Private Sub StartProgress()Dim i As IntegerFrame3.Visible = TrueX.Width = 1For i = 1 To 6255X.Width = X.Width + 1DoEventsNext

Frame3.Visible = FalseEnd Sub

Private Sub Command l_Click()connsqlstr ="select* from users where usemame="' & Textl.Text & '" and password='"

& Text2.Text & ""' Set rs= database.Execute(sqlstr)

StartProgress

If Not rs.EOF ThenIf rs![UserName] = Textl.Text And rs![Password] = Text2.Text Then

Unload MeElse

MsgBox "Error: Invalid Usemame or Password!!!", vbCriticalText 1.SetFocus

End IfElse

MsgBox "Error: Invalid Usemame or Password!!!", vbCriticalText 1. SetFocus

End IfEnd Sub

Private Sub conn()Set database= New ADODB.Connection

database.CursorLocation = adUseServer

61

sqlstr = "provider=Microsoft.jet.oledb.3.51; Data Source=" & App.Path & "\system.mdbll

database.Open sqlstrEnd Sub

The main menu form

Dim i As IntegerDim My_Name, My_Str As StringDim IsMoving As Boolean

Private Sub Commandl_Click(Index As Integer)Select Case Index

Case Is= O: Form2.Show vbModalCase Is= 1: Form5.Show vbModalCase Is= 2: Form6.Show vbModalCase Is= 3: Form9.Show vbModalCase Is= 4: FormlO.Show vbModalCase Is= 5: Call Form_QueryUnload(O, O)Case Is= 6: Form14.Show vbModalCase Is= 7: Form8.Show vbModal

End SelectEnd Sub

Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)IfMsgBox("Are you sure you want to exit?", vbYesNo + vbQuestion, "Exit")= vbYes

Then EndEnd Sub

Private Sub Timerl_Timer()Dim sString As String

My_Name = Left(Labell.Caption, 1)My_Str= Right(Labell.Caption, Len(Labell.Caption)- 1)

Label I.Caption= My_Str + My_Name

sString = "This Program Is Created By Ahmad Mohd Eid ... "

If Timerl.Tag = O ThenMe.Caption= sStringTimerl.Tag = 1

Elself Timerl.Tag < Len(sString) ThenMe.Caption= Right(sString, Len(sString) - Timerl .Tag)Timerl.Tag = Timerl.Tag + 1

62

Elself Timerl.Tag = Len(sString) ThenMe.Caption= sStringTimerl.Tag = O

End IfEnd Sub

The firm record form

Option Explicit

Private database As ADODB.ConnectionPrivate rs As ADODB.RecordsetPrivate sqlstr As String

Dim p As Panel

Private Sub cmdNewfrm_Click()Call clearCall coun

cmdStkEnt.Visible = FalsecmdfrmSav.Enabled = TruecmdfrmUpd.Enabled = FalsecmdfrmDel.Enabled = False

txtFrmN ame.SetFocusEnd Sub

Private Sub cmdStkMinlvl_ Click()Forml2.Show vbModal

End Sub

Private Sub cmdfrmSav _Click()Dim sql, rslt, rsltl

rslt = MsgBox("Do You Want To Save That?", vblnformation + vbYesNo, "Save")

If rslt = vbYes ThenIf txtFrmName.Text <>""And txtFrmPhn.Text <> ""And txtFrmFax.Text <> "" And txtFrmTax.Text <> '"'And txtFrmCity.Text <> "" And txtFrmAdd.Text <> "" Then

sql = "insert into firms(firmname, fırmcode, fırmphone, fırmfax, firmtaxno,firmcity, firmadres, fırmregdate) values("

sql = sql & 11111 & txtFrmName.Text & "',"

63

sql = sql & "" & txtFrmCode.Text & ","sql = sql & ""' & txtFrmPhn.Text & "',"sql = sql & ""' & txtFrmFax.Text & '","sql = sql & ""' & txtFrmTax.Text & "',"sql = sql & ""' & txtFrmCity & '","sql = sql & ""' & txtFmıAdd & "',"sql = sql & ""' & DtPckfnnRegDat.Value & "')"

database.Execute (sql)

Dim i As Integer

StartProgress

rsltl = MsgBox("Firm Information Save Successful! ",, "Saved")

Private Sub cmdfrmMain _Click()database. CloseUnload MeEnd SubPrivate Sub cmdfrmFnd _Click()Dim find As Integerconn

IfText7.Text =""ThenMsgBox "Error: Please select an employee first!", vbCriticalExit Sub

End If

find= Val(Text7.Text)sqlstr ="select* from firms where firmcode=" & find & ""

Set rs= database.Execute(sqlstr)Ifrs.EOF ThenMsgBox ("The Wanted Firm is Not Available!")ElseDim i As Integer

Startl'rogress

txtFrmCode.Text = rs![firmcode]txtFrmName.Text = rs![firmname]txtFrmPhn.Text = rs![fırmphone]txtFrmFax.Text = rs![firmfax]txtFrmTax.Text = rs![firmtaxno]txtFrmCity.Text = rs![fırmcity]

64

txtFrmAdd.Text = rs'[firmadres]DtPckfrmRegDat.Value = rs![firmregdate]txtFrmN ame.SetFocuscmdfrmSav.Enabled = FalsecmdfrmUpd.Enabled = TruecmdfrmDel.Enabled = TruecmdStkEnt.Visible = TrueEnd Ifrs.Close

End SubPrivate Sub cmdStkEnt_ Click()Form4.Textl.Text = txtFrmCode.TextForm4.Text2.Text = txtFrmName.TextForm4.Show vbModalEnd Sub

Private Sub Form_Load()counWith StatusBarl .Panels

Set p = .Add(, , , sbrTime)Set p = .Add(, , , sbrDate)

End WithDtPckfrmRegDat.Value = DateEnd SubPrivate Sub clear()txtFrmCode.Text = ""txtFrmName.Text = '"'txtFrmCity.Text = ""txtFrmAdd.Text = ""txtFrmPhn.Mask = ""txtFrmPhn.Text = ""txtFrmPhn.Mask = "0(999)999-99-99"txtFrmFax.Mask = ""txtFrmFax.Text = ""txtFrmFax.Mask = "0(999)999-99-99"txtFrmTax.Mask = ""txtFrmTax.Text = ""txtFrmTax.Mask = "999-999-999-999-999"DtPckfrmRegDat.Value = DateEnd SubPrivate Sub coun()Dim Count, Count 1connSet rs= New ADODB.RecordsetCount= "select * from Firms"Set rs= database.Execute(Count)

65

Ifrs.EOF ThencmdfrmFnd.Enabled = FalsetxtFrmCode.Text = 1ElseCountl = "select max(firmcode) as cis from firms"Set rs= database.Execute(Countl)txtFrmCode.Text = rs![cis] + 1End Ifrs.Close

End SubPublic Sub conn()Set database = New ADODB.Connection

database.CursorLocation = adUseServersqlstr = "provider=Microsoft.jet.oledb.3.51; Data Source=" & App.Path &

"\system.mdb"database. Open sqlstr

End SubPrivate Sub StartProgress()

Dim i As IntegerFrarnel .Visible= TrueX.Width = 1For i = 1 To 6255

X.Width = X.Width + 1DoEvents

Next

Frame 1 .Visible = False

End Sub

The stock record form

Option ExplicitPrivate database As ADODB.ConnectionPrivate rs As ADODB.RecordsetPrivate sqlstr As StringDim p As PanelDim ah As BooleanDim a, b, d, e, g, h, f, 1 As DoubleDim m, n, decrip, sql 1Private Sub Cornrnandl Click()clearcounCornrnand2.Enabled = TrueCornrnand3.Enabled = False

66

Command4.Enabled = FalseText-l.SetfocusEnd SubPrivate Sub Command2 _Click()If care Then Exit SubIf ah = True ThenDim sql, sqll. rslt, rsltlrslt = MsgBox("Do You Want To Save That?", vblnformation + vbYesNo, "Save")Ifrslt = vbYes ThenIfText4.Text <>""And Text5.Text <>""And Text6.Text <>""And Text8.Text <> ""And TextlO.Text <> 1111 And Textl 1.Text <>""Thensql = "insert into stocks(fırmname, fırmcode, stockcode, stockname, stockminl, stockbd,stockunit, stockbp, stockpperc, stocksellp) values("sql = sql & "'" & Text2.Text & "',"sql = sql & "'' & Textl.Text & ","sql = sql & "11 & Text3.Text & ","sql = sql & "'" & Text4.Text & "',"sql = sql & "" & Textl 1 & ","sql = sql & 11111 & Labell 1.Caption & "',"sql = sql & 1111 & a & 11,11

sql = sql & "" & b & 11,11

sql = sql & "" & h & ","sql = sql & 11111 & Text9 & "')"database.Execute (sql)m = Text5.Text1 = Text6.Textn=m * 1decrip = Text3 +","+"no"+ "st"sql 1 = "insert into account( accdate, expense, revenue, description, expcode) values("sqll = sqll & 111" & Labell I.Caption & "',"sqll = sqll & "" &n & ","sqll = sqll & "" & O & ","sqll = sqll & ""' & decrip & "',"sqll = sqll & "" & Text3.Text & ")"database.Execute (sqll)Dim i As Integer

StartProgress

rsltl = MsgBox("stock Information Save Successful! ", , "Saved")Command2.Enabled = FalseCommand3.Enabled = TrueCommand4.Enabled = TrueCommand6.Enabled = TrueElsersltl = MsgBox("Please Fill The Other Texts!")

67

Command3.Enabled = FalseCommand4.Enabled = FalseText4.SetFocusEnd IfEnd IfEnd IfEnd SubPrivate Sub Command6 _Click()Dim find As Integerconn

IfText7.Text =""ThenMsgBox "Error: Please select an employee first!", vbCriticalExit Sub

End If

find= Val(Text7.Text)sqlstr = "select * from stocks where stockcode=" & find & ""

Set rs= database.Execute(sqlstr)Ifrs.EOF ThenMsgBox ("The Wanted Stock is Not Available!")ElseDim i As Integer

StartProgress

Textl.Text = rs![firmcode]Text2.Text = rs![firmname]Text3.Text = rs![stockcode]Text4.Text = rs! [stockname]Text5.Text = rs![stockunit]Text6.Text = rs![stockbp]Text8.Text = rs![stockpperc]Text9.Text = rs![stocksellp]Labell 1.Caption = rs![stockbd]Textl 1.Text = rs![stockminl]Command2.Enabled = FalseCommand3.Enabled = TrueCommand4.Enabled = TrueEnd Ifrs.Close

End Sub

Private Sub Form_Load()counWith StatusBarl.Panels

68

-·-------

Set p = .Add(, , , sbrTime)Set p = .Add(, , , sbrDate)

End WithLabell l.Caption = DateEnd SubPrivate Sub Form_Unload(Cancel As Integer)Unload MeEnd Sub

Private Sub TextlO_Change()On Error Resume Nexta= Text5.Textb = Text6.Texth = Text8.Textd = Val(a) * Val(b)e = ((d * Val(h)) I 100) + df= e I ag = ((f * Val(TextlO.Text)) I 100) + f Text9.Text = g End SubPrivate Sub coun()Dim Count, Countl

conn

Set rs= New ADODB.RecordsetCount= "select* from stocks"

Set rs= database.Execute(Count)

Ifrs.EOF ThenCommand6.Enabled = FalseText3.Text = 1

ElseCountl = "select max(stockcode) as cis from stocks"Set rs= database.Execute(Countl)Text3.Text = rs![cis] + 1

End Ifrs.Close

End SubPublic Sub conn()Set database= New ADODB.Connection

database.CursorLocation = adUseClientsqlstr = "provider=Microsoft.jet.oledb.3 .51; Data Source=" & App.Path &

"\system.mdb"database.Open sqlstr

End Sub

69

Private Sub clear()Text4.Text = 1111

Text5.Text = 1111

Text6.Text = 1111

Text8.Text = 1111

Text9.Text = 1111

TextlO.Text = 1111

Textl 1 .Text= 1111

End Sub

Private Sub StartProgress()

Dim i As IntegerFrame2.Visible = TrueX.Width = 1For i = 1 To 6255

X.Width = X.Width + 1DoEvents

Next

Frame2.Visible = False

End Sub

Stock record Min level

Option ExplicitDim RST As New ADODB.RecordsetPrivate database As ADODB.ConnectionPrivate rs As ADODB.RecordsetPrivate sqlstr As StringPrivate Sub Commandl_Click()Unload MeIf Not Form2.Visible Then Form2.ShowEnd SubPrivate Sub Command2 _Click()Unload MeIf Not Forml .Visible Then Forml .ShowEnd Sub

Private Sub Form_Load()comEnd SubPrivate Sub com()On Error Resume Nextconne

70

Set RST = database.Execute("Select stockcode, stockname,firmcode, stockunit,stockminlfrom stocks where stockminl >= stockunit")Set DataGridl .DataSource = RSTDataGridl .Caption= "LIST OF :tviINIMUM LEVEL GREATER THAN AVAILABLESTOCK UNIT BY STOCKCODE"DataGridl .Columns(O).Caption = "StockCode"DataGridl.Columns(l).Caption = "StockName"DataGridl .Columns(2).Caption = "FirmCode"DataGridl .Columns(3).Caption = "StockUnit"DataGridl.Columns(4).Caption = "Stock Min.Level"DataGridl .Columns( 4).Alignment = dbgRightSelect Case RST.RecordCountCase Is> 1Labell .Caption= "Total " & Trim(Str(RST.RecordCount)) & " Min. Level>= StockQuantity Record Exist"Case Is= 1Labell.Caption = "Total " & Trim(Str(RST.RecordCount)) & "Min. Level>= StockQuantity Record Exist"Case Is= OLabell.Caption = "Record Not Exist"End SelectEnd SubPrivate Sub conne()Set database= New ADODB.Connection

database.CursorLocation = adUseClientsqlstr = "provider=Microsoft.jet.oledb.3.51; Data Source=" & App.Path &

"\system.mdb"database.Open sqlstr

End SubPrivate Sub Form_Unload(Cancel As Integer)Unload MeEnd Sub

Employee record form

Option ExplicitDim p As PanelPrivate database As ADODB.ConnectionPrivate rs As ADODB.RecordsetPrivate sqlstr As String

Private Sub cmdLdPic _Click()On Error GoTo ErrH

WithCDG.CancelError = True.DialogTitle = "Select Student Picture"

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.Flags= cdlOFNFileMustExist

.Filter= "JPEG Files(*.jpg)l*.jpg;*.jpeglBitmap Images(*.bmp)l*.bmplGIFFiles(* .gif)I*.gi~All Files(*. *)I*.*"

.Showüpen

If Not .FileName = vbNullString ThenIf CheckFile( .FileName) Then

PicEmp.Picture = LoadPicture(.FileName)PicEmp.Tag = .FileNamePicEmp.ToolTipText = "Picture Loaded: (" & .FileName & ")"

ElseMsgBox "Error: Picture Is Not Loaded!!!", vbCritical, "Error: Access Error"

End IfEnd WithExit Sub

ErrH:End Sub

Public Function CheckFile(FileN ame$) As BooleanOn Error GoTo FileNotFoundDimX&X = FileLen(FileName)IfX >= O Then CheckFile = True: Exit Function

FileNotFound:If Err.Number= 53 Then CheckFile = False: Exit Function

End Function

Private Sub Commandl Click()clearcounCommand2.Enabled = TrueCommand3.Enabled = FalseCommand4.Enabled = FalseText2. SetFocusEnd Sub

Private Sub SetEmpPic(DoSet As Boolean, EmpNum As String, objPic As PictureBox)If DoSet Then

Dim EmpPicFile As StringEmpPicFile = App.Path & "\Employers\" & EmpNum & ".jpg"

If CheckFile(EmpPicFile) = True ThenSet objPic.Picture = LoadPicture(EmpPicFile)

Else

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Set objPic.Picture = NothingMsgBox "Could Not Load Employers Picture!!!" & vbCrLf & "File Access

Error", vbCritical, "Error: File Error"End If

ElseobjPic.Picture = Nothing

End IfEnd Sub

Private Sub Command6_Click()Dim find As Integerconn

IfText6.Text =""ThenMsgBox "Error: Please select an employee first!", vbCriticalExit Sub

End If

find= Val(Text6.Text)sqlstr = "select * from emp where empcode=" & find & ""

Set rs= database.Execute(sqlstr)Ifrs.EOF Then

MsgBox ("The Wanted Employee is Not Available!")Call SetEmpPic(False, Textl.Text, PicEmp)

Else

StartProgress

Textl.Text = rs![EmpCode]Text2.Text = rs! [empname]

Call SetEmpPic(True, Textl.Text, PicEmp)

MaskEdBox 1 .Text = rs! [empphone]MaskEdBox3.Text = rs![empsc]

Text3.Text = rs![empcity]Text4.Text = rs![empadres]Text5.Text = rs! [empsal]

DTPickerl.Value = rs![emprd]

Text2.SetFocus

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Command2.Enabled = FalseCommand3 .Enabled = TrueCommand4.Enabled = True

End Ifrs.Close

End Sub

Private Sub Form_Load()counWith StatusBarl .Panels

Set p = .Add(, , , sbrTime)Set p = .Add(, , , sbrDate)

End WithDTPickerl.Value = DateEnd SubPrivate Sub clear()Textl .Text= ""Text2.Text = ""Text3.Text = ""Text4.Text = ""Text5.Text = ""MaskEdBoxl.Mask = ""MaskEdBoxl.Text = '"'MaskEdBoxl .Mask= "0(999)999-99-99"MaskEdBox3.Mask = ""MaskEdBox3.Text = ""MaskEdBox3.Mask = "999-999-999-999-999"DTPickerl.Value = DateEnd SubPrivate Sub coun()Dim Count, Count 1connSet rs= New ADODB.RecordsetCount= "select * from emp"Set rs= database.Execute(Count)

Ifrs.EOF ThenCommand6.Enabled = FalseTextl .Text= 1ElseCountl = "select max(empcode) as cis from emp"Set rs= database.Execute(Countl)Textl.Text = rs![cis] + 1End Ifrs.Close

End SubPublic Sub conn()

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Set database= New ADODB.Connectiondatabase.CursorLocation = adUseClientsqlstr = "provider=Microsoft.jet.oledb.3.51; Data Source=" & App.Path &

"\system.mdb"database.Open sqlstr

End Sub

Private Sub Text5_KeyPress(KeyAscii As Integer)If KeyAscii = 13 Then

KeyAscii = O SendKeys "{Tab}"

Elself InStr(("1234567890" & vbBack & ""), Chr(KeyAscii)) = O ThenKeyAscii = O

End IfEnd Sub

Private Sub StartProgress()

Dim i As IntegerFramel.Visible = TrueX.Width = 1For i = 1 To 6255

X.Width = X.Width + 1DoEvents

Next

Framel.Visible = False

End Sub

Customer record form

Option ExplicitDim p As PanelPrivate database As ADODB.ConnectionPrivate rs As ADODB.RecordsetPrivate sqlstr As StringPrivate Sub Commandl _Click()clearcounCommand2.Enabled = TrueCommand3.Enabled = FalseCommand4.Enabled = FalseCommand7.Visible = FalseText2.SetFocusEnd Sub

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Private Sub Command2 _Click()Dim sql, rslt, rsltlrslt = MsgBox("Do You Want To Save That?", vblnformation + vbYesNo, "Save")Ifrslt = vbYes ThenIfText2.Text <>""And MaskEdBoxl.Text <>""And Text3.Text <>""AndMaskEdBox3.Text <>""And Text3.Text <>""And Text4.Text <>""Thensql = "insert into cus(cusname, cuscode, cusphone, custaxno, cuscity, cusadres, cusrd)values("sql = sql & ""' & Text2.Text & "'," sql = sql & "" & Textl.Text & "," sql = sql & ""' & MaskEdBoxl.Text & "'," sql = sql & ""' & MaskEdBox3.Text & "'," sql = sql & ""' & Text3 & "'," sql = sql & ""' & Text4 & "'," sql = sql & ""' & DTPickerl.Value & "')" database.Execute (sql)

StartProgress

rsltl = MsgBox("Customer Information Save Successful! ",, "Saved")Command2.Enabled = FalseCommand3.Enabled = TrueCommand4.Enabled = TrueCommand7.Visible = TrueCommand6.Enabled = TrueElsersltl = MsgBox("Please Fill The Other Texts!", vbCritical, "Customer")Command6.Enabled = TrueCommand3.Enabled = FalseCommand4.Enabled = FalseText2.SetFocusEnd IfEnd IfEnd Sub

Private Sub Command6 _Click()Dim find As Integerconn

If Text6.Text = "" ThenMsgBox "Error: Please select an employee first!", vbCriticalExit Sub

End If

find= Val(Text6.Text)sqlstr ="select* from cus where cuscode=" & find & ""

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Set rs= database.Execute(sqlstr)If rs.EOF ThenMsgBox ("The Wanted Customer is Not Available!")Else

StartProgress

Textl.Text = rs![cuscode]Text2.Text = rs![cusname]MaskEdBoxl.Text = rs![cusphone]MaskEdBox3.Text = rs![custaxno]Text3.Text = rs![cuscity]Text4.Text = rs![cusadres]DTPickerl.Value = rs![cusrd]Text2. SetFocusCommand7.Visible = TrueCommand2.Enabled = FalseCommand3.Enabled = TrueCommand4.Enabled = TrueEnd Ifrs.Close

End SubPrivate Sub Command?_ Click()DimX$

X = "select empname from emp"Set rs = database.Execute(X)

Ifrs.EOF ThenMsgBox "Error: Employee table is empty," & vbNewLine & _ "Please add one employee at least before continuing.", vbCritical

Exit SubElse

Form7.Text4.Text = Textl.TextForm7.Text5.Text = Text2.TextForm7.Text7.Text = MaskEdBoxl.TextForm7.Text6.Text = Text4.TextForm7.Show vbModal

End IfEnd SubPrivate Sub Form_Load()counWith StatusBarl .Panels

Set p = .Add(, , , sbrTime)Set p = .Add(, , , sbrDate)

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End WithDTPickerl .Value= DateEnd SubPrivate Sub clear()Textl .Text= ""Text2.Text = ""Text3.Text = ""Text4.Text = ""MaskEdBoxl.Mask = ""MaskEdBoxl.Text = ""MaskEdBoxl .Mask= "0(999)999-99-99"MaskEdBox3.Mask = ""MaskEdBox3.Text = ""MaskEdBox3.Mask = "999-999-999-999-999"DTPickerl.Value = DateEnd SubPrivate Sub coun()Dim Count, CountlconnSet rs = New ADODB.RecordsetCount= "select* from cus"Set rs= database.Execute(Count)

Ifrs.EOF ThenCommand6.Enabled = FalseTextl.Text = 1ElseCountl = "selectmax(cuscode) as cis from cus"Set rs= database.Execute(Countl)Textl.Text = rs![cis] + 1End Ifrs.Close

End SubPublic Sub conn()Set database= New ADODB.Connection

database.CursorLocation= adUseClientsqlstr = "provider=Microsoft.jet.oledb.3.51;Data Source="& App.Path &

"\system.mdb"database.Opensqlstr

End Sub

Private Sub StartProgress()

Dim i As IntegerFramel.Visible= TrueX.Width= 1For i = 1 To 6255

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X.Width = X.Width + 1DoEvents

Next

Frame 1 .Visible = FalseEnd SubThe invoice form

Option ExplicitPrivate database As ADODB.ConnectionPrivate rs, RSl, RS3 As ADODB.RecordsetPrivate sqlstr As StringPrivate sql, sql 1, sql2, sql3 As String

Private Sub Combo2_Click()Text8.Text = List2.List(Combo2.Listlndex)Text8.SetFocusSendKeys " {enter}"

End Sub

Private Sub coun()Dim Count, CountlconnSet rs= New ADODB.RecordsetCount= "select incode from invoice2"Set rs= database.Execute(Count)

lfrs.EOF ThenLabel9.Caption = 1ElseCountl = "select max(incode) as cis from invoice2"Set rs= database.Execute(Countl)Label9.Caption = rs![cis] + 1End If

Count= "select empname from emp"Set rs= database.Execute(Count)

Ifrs.EOF ThenMsgBox "Error: Employee table is empty," & vbNewLine & _ "Please add one employee at least before continuing.", vbCriticalCall Command 1 ClickExit SubElseCountl = "select empname from emp"Set rs= database.Execute(Countl)While Not rs.EOFCombo 1 .Addltem rs.Fields! [empname]rs.MoveNext

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DoEventsWendEnd Ifrs.Close

End SubPrivate Sub Command4_Click()

Dim k, i, rslt, toplam, stk, stk2, sq, sql, sq2, decrip

If Combol.Text = "Select Employee" Thenrslt = MsgBox("Please select the employee name", vbinformation, "Invoice")

ElselfListl(O).ListCount = O Thenrslt = MsgBox("Please select one stock at least", vbInformation, "Invoice")

Elserslt = MsgBox("Do You Want to Save The Invoice?", vbYesNo + vbQuestion,

"Invoice Saving")If rslt = vbYes Then

connFor i = O To Listl (O).ListCount - 1

stk = Val(Listl(O).List(i))stk2 = Listl(l).List(i)

sq= Val(List1(2).List(i))sql = Val(List1(3).List(i))sq2 = Val(List1(4).List(i))

sqll = "insert into invoicel(incode, cuscode, stockcode, sname, quan, uprice,totp) values ("

sqll = sqll & "" & Label9 & ","sqll = sqll & "" & Text4.Text & ","sqll = sqll & "" & stk & ","sqll = sqll & ""' & stk2 & "',"sqll = sqll & "" & sq & ","sqll = sqll & "" & sql & ","sqll = sqll & "" & sq2 & ")"

database.Execute (sqll)sql2 = "update stocks set stockunit=stockunit-" & sq & "where stockcode=" &

stk & "" database.Execute (sql2)

Next

If Option 1 = True Thentoplam= Odecrip = Label9 +","+"no"+ "Invoice"

80

sql3 = "insert into account(accdate, expense, revenue, description, expcode)values("' & Label12 & "', " & O & "," & Text2.Text & ","' & decrip & "'," & toplam & ")"

database.Execute (sql3)

Elself Option2 = True Thentoplam= Text2.Text

End If

Private Sub Form_Activate()On Error Resume NextDim MySql$Text8.SetFocusconnMySql = "select stockname, stockcode from stocks"Set RS3 = database.Execute(MySql)

Combo2.clear

Do While Not RS3.EOFCombo2 .Addltem RS3 ! [stockname]List2 .Addltem RS3 ! [ stockcode]DoEventsRS3 .MoveN extDoEvents

LoopEnd SubPrivate Sub Form_Load()Optionl = TrueLabel 12 = DatecounEnd Sub

Private Sub Listl _Click(Index As Integer)Dim secind, topin, j On Error Resume Nextsecind = Listl (Index).Listlndextopin = Listl(Index).ToplndexFor j = O To 4 Listl (j).Listlndex = secindListl(j).Toplndex = topinNextEnd Sub

81

Private Sub Textl l_KeyPress(KeyAscii As Integer)Dim ansIf KeyAscii = 13 ThenKeyAscii = Olf Val(Textl 1 .Text)> Val(Text9.Text) Thenans= MsgBox("Stock not enough to sell this amount I Available stock is=" & Text9 & "unit" vbCritical "Invoice")' ' ElselfVal(Textl I.Text)<= O Then

MsgBox "Error: Quantity Error, At least 1 item should be sold!!!", vbCriticalExit Sub

End IfListl(O).Addltem Text8.TextListl(l).Addltem Combo2.TextList1(2).Addltem Textl I.TextList1(3).Addltem TextlO.TextList1(4).Addltem (Val(Textlü.Text) * Val(Textl 1.Text))Textl I.Enabled= FalseClear AllText8.Text = ""Text8.SetFocusDimi, a, bFor i = O To List1(4).ListCounta= Val(List1(4).List(i))b=b+aNextText2.Text = bEnd IfElself InStr(("1234567890" & vbBack & ""), Chr(KeyAscii)) = O Then

KeyAscii = OEndlfEnd SubPrivate Sub conn()Set database= New ADODB.Connection

database.CursorLocation = adUseClientsqlstr = "provider=Microsoft.jet.oledb.3.51; Data Source=" & App.Path &

"\system.mdb"database.Open sqlstr

End SubPublic Sub ClearAll()Text8.Text = ""Combo2.Text = ""Text9.Text = ""Textl O.Text= ""Textl 1 .Text=""End Sub

82

The account revenue form

Option ExplicitDim rs, RSI, RS2, RS3 As New ADODB.RecordsetPrivate DB As ADODB.ConnectionPrivate RST As ADODB.RecordsetPrivate ConnStr As StringDim sqlstr, textq, a, decrip, b, c, rslt

Private Sub Commandl_Click()If Optionl.Value = True ThenOn Error Resume NextIfTextl.Text =""ThenMsgBox "Please Enter The Selected Criteria!", vbCritical, "Account"Framel .Visible= FalseTextl .SetFocusElseconnesqlstr = "select incode, cuscode, invdate, empname, subtot from invoice2 where incode =" & Textl.Text & "and subtot>O"Set rs= DB.Execute(sqlstr)Ifrs.EOF ThenMsgBox "Wanted Invoice Does Not Exist!", vbCritical, "Account"Label2.Visible = FalseLabel3.Visible = FalseFramel .Visible= FalseElsetextq = "select sum(subtot) as com from invoice2 where incode=" & Textl.Text & '"' Set RS 1 = DB.Execute(textq)a = rs! [cuscode]Set DG.DataSource = rsCall SetGridDataLabel3. Caption = RS 1 ! [com]Label2.Visible = TrueLabel3.Visible = TrueFramel.Visible = TrueEnd IfEnd IfEnd IfIf Option2 = True ThenOn Error Resume NextIf Textl .Text= "" ThenMsgBox "Please Enter The Selected Criteria!", vbCritical, "Account"Framel .Visible= FalseTextl .SetFocusElse

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connesqlstr = "select incode, cuscode, invdate, empname, subtot from invoice2 where cuscode= " & Textl .Text & " and Subtot>O "Set rs= DB.Execute(sqlstr)Ifrs.EOF ThenMsgBox "Wanted Customer No Not Exist!", vbCritical, "Account"Label2.Visible = FalseLabel3.Visible = FalseFramel.Visible = FalseElsetextq = "select sum(subtot) as com from invoice2 where cuscode=" & Textl.Text & "" Set RSl = DB.Execute(textq)a= rs! [cuscode]Call SetGridDataLabel3. Caption = RS 1 ! [com]Label2.Visible = TrueLabel3.Visible = TrueFramel .Visible= TrueEnd IfEnd IfEnd IfTextl .Text= ""Textl .SetFocusEnd Sub

Private Sub Form_Load()Label12.Caption = DatecomtotCommandl .Enabled= FalseEnd SubPrivate Sub comtot()On Error Resume NextconneSet rs= DB.Execute("Select incode, cuscode, invdate, empname, subtot from invoice2where subtot >O")Set DG.DataSource = rsCall SetGridDataSelect Case rs.RecordCountCase Is> 1Label8.Caption = "Total " & Trim(Str(rs.RecordCount)) & " Record Exist"Case Is= 1Label8.Caption = "Total " & Trim(Str(rs.RecordCount)) & " Record Exist"Case Is= OLabel8.Caption = "Record Not Exist"End SelectEnd Sub

84

Private Sub Option2 _Click()Label5.Visible = TrueLabel6.Visible = FalseTextl .SetFocusComınandl .Enabled= TrueEnd SubPrivate Sub SetOridData()Set DO.DataSource = rsDO.RefreshDO.Caption= "LIST OF INVOICE BY CUSTOMER CODE"DO.Columns(O).Caption = "Invoice No"DO.Columns(l).Caption = "Customer No"DO.Columns(2).Caption = "Invoice Date"DO.Columns(3).Caption = "Employee Name"DO.Columns(4).Caption = "Invoice Amount"DO.Columns(4).Alignment = dbgRightEnd Sub

The user management form

Private database As ADODB.ConnectionPrivate rs As ADODB.RecordsetPrivate sqlstr As String

Private Sub Checkl_Click()txtpass.PasswordChar = Ilf(Checkl .Value= vbChecked, "", "*")

End Sub

Private Sub cmdNewfrm_Click()On Error Resume Next

Call DoClearCall coun

cmdfrmSav.Enabled = TruecmdfrmUpd.Enabled = FalsecmdfrmDel.Enabled = False

txtusm. SetFocusEnd Sub

Private Sub cmdfrmSav _Click()Dim sql, rslt, rsltl

rslt = MsgBox("Do You Want To Save That?", vblnformation + vbYesNo, "Save")

If rslt = vbYes Then

85

If txtusm.Text <> 1111 And txtpass.Text <> 1111 Then

sql = "insert into users(usemame, password) values("' & txtusm.Text & "', "' &txtpass.Text & 111)11

database.Execute (sql)

StartProgress

rsltl = MsgBox("User was saved successfully! ", , "Saved")

cmdfrmSav.Enabled = FalsecmdfrmUpd.Enabled = TruecmdfrmDel.Enabled = TruecmdfrmFnd.Enabled = True

Elsersltl = MsgBox("Please Fill All Texts!")

cmdfrmUpd.Enabled = FalsecmdfrmDel.Enabled = FalsecmdfrmFnd.Enabled = Truetxtusm.SetFocus

End IfEnd If

End Sub

Private Sub cmdfrmUpd _Click()Dim rslt As StringIftxtusm.Text <>'"'And txtpass.Text <>""Thenrslt = MsgBox("Do You Want To Update User Information?", vbCritical + vbYesNo,"Update")If rslt = vbYes ThenStartProgressconnsqlstr = "update users set usemame="' & txtusm.Text & "', password="' & txtpass.Text &111 where usemame="' & txtusm.Text & 11111

database.Execute (sqlstr)MsgBox ("User Information Updated!")End IfElseMsgBox ("Please Find User First!")End IfcmdfrmUpd.Enabled = FalsecmdfrmDel.Enabled = FalseEnd Sub

86

Private Sub cmdfrmFnd _Click()On Error Resume NextDim find As Stringconn

IfText7.Text =""ThenMsgBox "Error: Please select an employee first!", vbCriticalExit Sub

End If

find= Text7.Textsqlstr ="select* from users where usenıame="' & find & ""'

Set rs= database.Execute(sqlstr)Ifrs.EOF ThenMsgBox ("The Wanted User Was NotFound!")ElseDim i As Integer

StartProgress

txtusnı.Text = rs![UserName]txtpass.Text = rs![Password]

txtusnı. SetFocus

cmdfrmSav.Enabled = FalsecmdfrmUpd.Enabled = TruecmdfrmDel.Enabled = TrueEnd Ifrs.Close

End Sub

Private Sub Command!_ Click()Listl .clearsqlstr = "select username from users"Set rs= database.Execute(sqlstr)

DoEvents

If Not rs.EOF ThenWhile Not rs.EOF

Listl .Addltem rs.Fields! [UserName]rs.MoveNextDoEvents

Wend

87

End IfEnd Sub

Private Sub StartProgress()

Dim i As IntegerFrame2.Visible = TrueX.Width= 1For i = 1 To 6975

X.Width = X.Width + 1DoEvents

Next

Frame2.Visible = False

End Sub

Private Sub Listl_Click()Text7 .Text= Listl .List(Listl .Listlndex)Call cmdfrmFnd Click

End Sub

The reports form

Option Explicit

Private Sub Commandl_Click(Index As Integer)StartProgressSelect Case Index

Case Is = O: DataReportl .Show vbModalCase Is= 1: DataReport2.Show vbModalCase Is= 2: DataReport3.Show vbModalCase Is= 3: DataReport4.Show vbModalCase Is= 4: DataReport5.Show vbModal

End SelectEnd Sub

Private Sub Command2 _Click()Unload Me

End Sub

Private Sub StartProgress()

Dim i As IntegerFramel.Visible = TrueX.Width = 1

88

For i = 1 To 6255X.Width = X.Width + 1DoEvents

NextFramel.Visible = False

DoEventsEnd SubThe about form Option Explicit

Private Sub Timerl_Timer()Imagel.Top = Imagel.Top - 10

Iflmagel.Top <= -12360 ThenTimerl .Enabled = False

End IfEnd Sub

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